aarch64: Add support for fp8fma instructions

The AArch64 FEAT_FP8FMA extension introduces instructions for
multiply-add of vectors.

This patch introduces the following instructions:
1. {vmlalbq|vmlaltq}_f16_mf8_fpm.
2. {vmlalbq|vmlaltq}_lane{q}_f16_mf8_fpm.
3. {vmlallbbq|vmlallbtq|vmlalltbq|vmlallttq}_f32_mf8_fpm.
4. {vmlallbbq|vmlallbtq|vmlalltbq|vmlallttq}_lane{q}_f32_mf8_fpm.

It introduces the fp8fma flag.

gcc/ChangeLog:

	* config/aarch64/aarch64-builtins.cc
	(check_simd_lane_bounds): Add support for new unspecs.
	(aarch64_expand_pragma_builtins): Add support for new unspecs.
	* config/aarch64/aarch64-c.cc
	(aarch64_update_cpp_builtins): New flags.
	* config/aarch64/aarch64-option-extensions.def
	(AARCH64_OPT_EXTENSION): New flags.
	* config/aarch64/aarch64-simd-pragma-builtins.def
	(ENTRY_FMA_FPM): Macro to declare fma intrinsics.
	(REQUIRED_EXTENSIONS): Define to declare functions behind
	command line flags.
	* config/aarch64/aarch64-simd.md:
	(@aarch64_<fpm_uns_op><VQ_HSF:mode><VQ_HSF:mode><V16QI_ONLY:mode><V16QI_ONLY:mode): Instruction pattern for fma intrinsics.
	(@aarch64_<fpm_uns_op><VQ_HSF:mode><VQ_HSF:mode><V16QI_ONLY:mode><VB:mode><SI_ONLY:mode): Instruction pattern for fma intrinsics with lane.
	* config/aarch64/aarch64.h
	(TARGET_FP8FMA): New flag for fp8fma instructions.
	* config/aarch64/iterators.md: New attributes and iterators.
	* doc/invoke.texi: New flag for fp8fma instructions.

gcc/testsuite/ChangeLog:

	* gcc.target/aarch64/simd/fma_fpm.c: New test.