aarch64: [SME] Add SME mode selection and state access instructions

aarch64: [SME] Add SME mode selection and state access instructions

This patch is adding new SME mode selection and state access instructions:
* Add SMSTART and SMSTOP instructions.
* Add SVCR system register.

gas/ChangeLog:

	* config/tc-aarch64.c (parse_sme_sm_za): New parser.
	(parse_operands): New parser.
	* testsuite/gas/aarch64/sme-8-illegal.d: New test.
	* testsuite/gas/aarch64/sme-8-illegal.l: New test.
	* testsuite/gas/aarch64/sme-8-illegal.s: New test.
	* testsuite/gas/aarch64/sme-8.d: New test.
	* testsuite/gas/aarch64/sme-8.s: New test.

include/ChangeLog:

	* opcode/aarch64.h (enum aarch64_opnd): New operand
	AARCH64_OPND_SME_SM_ZA.
	(enum aarch64_insn_class): New instruction classes
	sme_start and sme_stop.

opcodes/ChangeLog:

	* aarch64-asm.c (aarch64_ins_pstatefield): New inserter.
	(aarch64_ins_sme_sm_za): New inserter.
	* aarch64-dis.c (aarch64_ext_imm): New extractor.
	(aarch64_ext_pstatefield): New extractor.
	(aarch64_ext_sme_sm_za): New extractor.
	* aarch64-opc.c (operand_general_constraint_met_p):
	New pstatefield value for SME instructions.
	(aarch64_print_operand): Printout for OPND_SME_SM_ZA.
	(SR_SME): New register SVCR.
	* aarch64-opc.h (F_REG_IN_CRM): New register endcoding.
	* aarch64-opc.h (F_IMM_IN_CRM): New immediate endcoding.
	(PSTATE_ENCODE_CRM): Encode CRm field.
	(PSTATE_DECODE_CRM): Decode CRm field.
	(PSTATE_ENCODE_CRM_IMM): Encode CRm immediate field.
	(PSTATE_DECODE_CRM_IMM): Decode CRm immediate field.
	(PSTATE_ENCODE_CRM_AND_IMM): Encode CRm and immediate
	field.
	* aarch64-tbl.h (struct aarch64_opcode): New SMSTART
	and SMSTOP instructions.
	aarch64-asm-2.c: Regenerate.
	aarch64-dis-2.c: Regenerate.
	aarch64-opc-2.c: Regenerate.