aarch64: Add LSE128 instruction operand support

aarch64: Add LSE128 instruction operand support

Given the particular encoding of the LSE128 instructions, create the
necessary shared input+output operand register description and
handling in the code to allow for the encoding of the LSE128 128-bit
atomic operations.

gas/ChangeLog:

	* config/tc-aarch64.c (parse_operands):

include/ChangeLog:

	* opcode/aarch64.h (enum aarch64_opnd):

opcodes/ChangeLog:

	* aarch64-opc.c (fields):
	(aarch64_print_operand):
	* aarch64-opc.h (enum aarch64_field_kind):
	* aarch64-tbl.h (AARCH64_OPERANDS):