Unable to use SPI1 when enabled without SPI0 on cc13xx/cc26xx

[vanti]

Describe the bug
Similar to the issue for UARTs fixed in #25647, one is unable to use SPI1 unless SPI0 is enable in DTS.

To Reproduce
Steps to reproduce the behavior:

1. Modify boards/arm/cc1352r1_launchxl/cc1352r1_launchxl.dts to enable spi1

&spi1 {
        status = "okay";
        sck-pin = <10>;
        mosi-pin = <9>;
        miso-pin = <8>;
        cs-pin = <11>;
        cs-gpios = <&gpio0 11 0>;
};

2. Modify tests/drivers/spi/spi_loopback/boards/cc1352r1_launchxl.conf to use SPI_1:
   CONFIG_SPI_LOOPBACK_DRV_NAME="SPI_1"

3. cd tests/drivers/spi/spi_loopback

4. west build -b cc1352r1_launchxl

5. west flash

6. See error:

*** Booting Zephyr OS build v2.3.0-rc1-341-g2972cdc7632f  ***
Running test suite test_spi
===================================================================
starting test - test_spi_loopback
I: SPI test on buffers TX/RX 0x200000c5/0x200005d6
I: SPI test slow config
I: Start complete multiple
I: CS control inhibited (no GPIO device)
E: ***** BUS FAULT *****
E:   Precise data bus error
E:   BFAR Address: 0x40008004
E: r0/a1:  0x40008000  r1/a2:  0x02dc6c00  r2/a3:  0x10000000
E: r3/a4:  0x00006717 r12/ip:  0x00000009 r14/lr:  0x00003045
E:  xpsr:  0x61000000
E: Faulting instruction address (r15/pc): 0x00002f2e
E: >>> ZEPHYR FATAL ERROR 0: CPU exception on CPU 0
E: Current thread: 0x20000178 (unknown)
E: Halting system

Expected behavior
The test should pass.

Impact
This prevents a user from using SPI1 without enabling SPI0, leading to slower boot time, higher power consumption, etc.

Environment (please complete the following information):

• OS: Ubuntu 18.04
• Toolchain (e.g Zephyr SDK, ...): Zephyr SDK 0.11.3
• Commit SHA or Version used: 2972cdc

Additional context
Add any other context about the problem here.