arch: arm: Remove extraneous root cmake files

The ARM architecture root directory contains `aarch32.cmake` and
`aarch64.cmake` files whose contents are better suited to go into other
more purpose-specific files.

This commit removes the aforementioned files and moves their contents
to other files following the convention used by other architectures.

Signed-off-by: Stephanos Ioannidis <root@stephanos.io>

arch/arm/CMakeLists.txt

@@ -1,7 +1,11 @@
 # SPDX-License-Identifier: Apache-2.0
 
 if(CONFIG_ARM64)
-  include(aarch64.cmake)
+  set_property(GLOBAL PROPERTY PROPERTY_OUTPUT_FORMAT elf64-littleaarch64)
+
+  add_subdirectory(core/aarch64)
 else()
-  include(aarch32.cmake)
+  set_property(GLOBAL PROPERTY PROPERTY_OUTPUT_FORMAT elf32-littlearm)
+
+  add_subdirectory(core/aarch32)
 endif()

cmake/compiler/gcc/target_arm.cmake

@@ -15,6 +15,23 @@ else()
     list(APPEND TOOLCHAIN_LD_FLAGS  -mthumb)
   endif()
 
+  set(ARCH_FOR_cortex-m0        armv6s-m        )
+  set(ARCH_FOR_cortex-m0plus    armv6s-m        )
+  set(ARCH_FOR_cortex-m3        armv7-m         )
+  set(ARCH_FOR_cortex-m4        armv7e-m        )
+  set(ARCH_FOR_cortex-m23       armv8-m.base    )
+  set(ARCH_FOR_cortex-m33       armv8-m.main+dsp)
+  set(ARCH_FOR_cortex-m33+nodsp armv8-m.main    )
+  set(ARCH_FOR_cortex-r4        armv7-r         )
+  set(ARCH_FOR_cortex-r5        armv7-r+idiv    )
+
+  if(ARCH_FOR_${GCC_M_CPU})
+      set(ARCH_FLAG -march=${ARCH_FOR_${GCC_M_CPU}})
+  endif()
+
+  list(APPEND TOOLCHAIN_C_FLAGS -mabi=aapcs ${ARCH_FLAG})
+  list(APPEND TOOLCHAIN_LD_FLAGS -mabi=aapcs ${ARCH_FLAG})
+
   # Defines a mapping from GCC_M_CPU to FPU
 
   if(CONFIG_CPU_HAS_FPU_DOUBLE_PRECISION)