[BINUTILS, AArch64, 2/2] Update Store Allocation Tag instructions

[BINUTILS, AArch64, 2/2] Update Store Allocation Tag instructions

This patch updates the Store allocation tags instructions in
Armv8.5-A Memory Tagging Extension. This is part of the changes
that have been introduced recently in the 00bet10 release

All of these instructions have an updated register operand (Xt -> <Xt|SP>)

- STG <Xt|SP>, [<Xn|SP>, #<simm>]
- STG <Xt|SP>, [<Xn|SP>, #<simm>]!
- STG <Xt|SP>, [<Xn|SP>], #<simm>
- STZG <Xt|SP>, [<Xn|SP>, #<simm>]
- STZG <Xt|SP>, [<Xn|SP>, #<simm>]!
- STZG <Xt|SP>, [<Xn|SP>], #<simm>
- ST2G <Xt|SP>, [<Xn|SP>, #<simm>]
- ST2G <Xt|SP>, [<Xn|SP>, #<simm>]!
- ST2G <Xt|SP>, [<Xn|SP>], #<simm>
- STZ2G <Xt|SP>, [<Xn|SP>, #<simm>]
- STZ2G <Xt|SP>, [<Xn|SP>, #<simm>]!
- STZ2G <Xt|SP>, [<Xn|SP>], #<simm>

In order to accept <Rt|SP> a new operand type Rt_SP is introduced which has
the same field as FLD_Rt but follows other semantics of Rn_SP.

*** gas/ChangeLog ***

2019-04-11  Sudakshina Das  <sudi.das@arm.com>

	* config/tc-aarch64.c (process_omitted_operand): Add case for
	AARCH64_OPND_Rt_SP.
	(parse_operands): Likewise.
	* testsuite/gas/aarch64/armv8_5-a-memtag.d: Update tests.
	* testsuite/gas/aarch64/armv8_5-a-memtag.s: Likewise.
	* testsuite/gas/aarch64/illegal-memtag.l: Likewise.
	* testsuite/gas/aarch64/illegal-memtag.s: Likewise.

*** include/ChangeLog ***

2019-04-11  Sudakshina Das  <sudi.das@arm.com>

	* opcode/aarch64.h (enum aarch64_opnd): Add AARCH64_OPND_Rt_SP.

*** opcodes/ChangeLog ***

2019-04-11  Sudakshina Das  <sudi.das@arm.com>

	* aarch64-opc.c (aarch64_print_operand): Add case for
	AARCH64_OPND_Rt_SP.
	(verify_constraints): Likewise.
	* aarch64-tbl.h (QL_LDST_AT): Update to add SP qualifier.
	(struct aarch64_opcode): Update stg, stzg, st2g, stz2g instructions
	to accept Rt|SP as first operand.
	(AARCH64_OPERANDS): Add new Rt_SP.
	* aarch64-asm-2.c: Regenerated.
	* aarch64-dis-2.c: Regenerated.
	* aarch64-opc-2.c: Regenerated.