arm: Add support for Armv9.1-A to Armv9.3-A

arm: Add support for Armv9.1-A to Armv9.3-A

This patch adds AArch32 support for -march=armv9.[123]-a.
The behaviour of the new options can be expressed using a
combination of existing feature flags and tables.

The cpu_arch_ver entries for ARM_ARCH_V9_2A and ARM_ARCH_V9_3A
are technically redundant but it seemed less surprising to include
them anyway.

include/
	* opcode/arm.h (ARM_ARCH_V9_1A, ARM_ARCH_V9_2A): New macros.
	(ARM_ARCH_V9_3A): Likewise.

gas/
	* doc/c-arm.texi: Add armv9.1-a, armv9.2-a and armv9.3-a.
	* config/tc-arm.c (armv91a_ext_table, armv92a_ext_table): New macros.
	(armv93a_ext_table): Likewise.
	(arm_archs): Add armv9.1-a, armv9.2-a and armv9.3-a.
	(cpu_arch_ver): Add ARM_ARCH_V9_1A, ARM_ARCH_V9_2A and ARM_ARCH_V9_3A.
	* NEWS: Mention the above.
	* testsuite/gas/arm/attr-march-armv9_1-a.d: New test.
	* testsuite/gas/arm/attr-march-armv9_2-a.d: Likewise.
	* testsuite/gas/arm/attr-march-armv9_3-a.d: Likewise.
	* testsuite/gas/arm/bfloat16-armv9.1-a.d: Likewise.
	* testsuite/gas/arm/bfloat16-armv9.2-a.d: Likewise.
	* testsuite/gas/arm/bfloat16-armv9.3-a.d: Likewise.
	* testsuite/gas/arm/i8mm-armv9.1-a.d: Likewise.
	* testsuite/gas/arm/i8mm-armv9.2-a.d: Likewise.
	* testsuite/gas/arm/i8mm-armv9.3-a.d: Likewise.