[HELP] Usage of CMAKE_SYSTEM_PROCESSOR

[no1wudi]

Description

I have a question. It seems that many other projects use the architecture name as the value for CMAKE_SYSTEM_PROCESSOR. For example, for Cortex-M0, it should be set to armv6m. However, if we directly set it to the CPU type now, we may encounter compatibility issues with some libraries:

nuttx/arch/arm/src/cmake/platform.cmake

Lines 25 to 31 in b37a527

	if(CONFIG_ARCH_CORTEXM0)
	set(CMAKE_SYSTEM_PROCESSOR cortex-m0)
	elseif(CONFIG_ARCH_CORTEXM3)
	set(CMAKE_SYSTEM_PROCESSOR cortex-m3)
	elseif(CONFIG_ARCH_CORTEXM4)
	set(CMAKE_SYSTEM_PROCESSOR cortex-m4)
	elseif(CONFIG_ARCH_CORTEXM7)

For the 3rd party lib, such as iree and openamp
https://github.com/iree-org/iree/blob/6cdb40cf6ebe1eea457dc4bd5bbdb9d1a60ad5a0/build_tools/cmake/iree_macros.cmake#L49-L72

https://github.com/OpenAMP/open-amp/blob/8c0c0c386b5799b54faf9613a191f66dee76e400/README.md?plain=1#L173

Should we modify the definition to this more commonly used form? Doing so could improve compatibility with other 3rd party libraries.

Verification

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[xiaoxiang781216]

cmake option is copied from makefile, we need update both