Fix for Accton platform build failure while doing incremental build

[FuzailBrcm]

Why I did it

PDDF kernel modules symbols are required while building Accton platform modules e.g. AS9716, AS7726, AS7816 etc. When a fresh clone is done and build is triggered, then 'sonic-platform-pddf_1.1_amd64.deb' pkg gets built and symvars file is backed up. This is used in Accton platforms kernel modules build.

However (since the DPKG_CACHE is enabled) if PDDF pkg is picked from the cache then the symvers file is not generated and hence Accton platform kernel modules build would fail.

make[2]: Entering directory '/usr/src/linux-headers-5.10.0-8-2-amd64'
WARNING: Symbol version dump "/sonic/platform/broadcom/sonic-platform-modules-accton/as7726-32x/modules/../../../../pddf/i2c/Module.symvers.PDDF" is missing.
         Modules may not have dependencies or modversions.
  MODPOST /sonic/platform/broadcom/sonic-platform-modules-accton/as7726-32x/modules/Module.symvers
ERROR: modpost: "access_psu_model_name" [/sonic/platform/broadcom/sonic-platform-modules-accton/as7726-32x/modules/pddf_custom_psu.ko] undefined!
ERROR: modpost: "access_psu_serial_num" [/sonic/platform/broadcom/sonic-platform-modules-accton/as7726-32x/modules/pddf_custom_psu.ko] undefined!
make[4]: *** [/usr/src/linux-headers-5.10.0-8-2-common/scripts/Makefile.modpost:124: /sonic/platform/broadcom/sonic-platform-modules-accton/as7726-32x/modules/Module.symvers] Error 1
make[4]: *** Deleting file '/sonic/platform/broadcom/sonic-platform-modules-accton/as7726-32x/modules/Module.symvers'
make[3]: *** [/usr/src/linux-headers-5.10.0-8-2-common/Makefile:1749: modules] Error 2
make[2]: *** [/usr/src/linux-headers-5.10.0-8-2-common/Makefile:185: __sub-make] Error 2
make[2]: Leaving directory '/usr/src/linux-headers-5.10.0-8-2-amd64'
running build
running build_py

How I did it

I added a 'derived package' called sonic-platform-pddf-sym which contains the files required for supporting other platform's build. This derived package wont be the part of the final binary, but used only during the build-time. Added dependency for Accton platforms on this new derived package.

How to verify it

After the first build, make some small changes in Accton platform AS7726's kernel module driver file and trigger the Accton pkg re-build. Check if AS7726 kernel modules are built properly.

Which release branch to backport (provide reason below if selected)

• 201811
• 201911
• 202006
• 202012
• 202106
• 202111

Description for the changelog

Link to config_db schema for YANG module changes

A picture of a cute animal (not mandatory but encouraged)

[FuzailBrcm]

@Kalimuthu-Velappan @jostar-yang
Please review this PR

[FuzailBrcm]

/azpw run Azure.sonic-buildimage

[mssonicbld]

/AzurePipelines run Azure.sonic-buildimage

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Azure Pipelines successfully started running 1 pipeline(s).

[FuzailBrcm]

/azpw run Azure.sonic-buildimage

[mssonicbld]

/AzurePipelines run Azure.sonic-buildimage

[azure-pipelines]

Azure Pipelines successfully started running 1 pipeline(s).

[Kalimuthu-Velappan]

@Kalimuthu-Velappan @jostar-yang Please review this PR

Changes look fine

[adyeung]

@prgeor pls help review and signoff