bpf: opcodes, gas: support for signed register move V4 instructions

bpf: opcodes, gas: support for signed register move V4 instructions

This commit adds the signed register move (movs) instructions
introduced in the BPF ISA version 4, including opcodes and assembler
tests.

Tested in bpf-unknown-none.

include/ChangeLog:

2023-07-21  Jose E. Marchesi  <jose.marchesi@oracle.com>

	* opcode/bpf.h (BPF_OFFSET16_MOVS8): Define.
	(BPF_OFFSET16_MOVS16): Likewise.
	(BPF_OFFSET16_MOVS32): Likewise.
	(enum bpf_insn_id): Add entries for MOVS{8,16,32}R and
	MOVS32{8,16,32}R.

opcodes/ChangeLog:

2023-07-21  Jose E. Marchesi  <jose.marchesi@oracle.com>

	* bpf-opc.c (bpf_opcodes): Add entries for MOVS{8,16,32}R and
	MOVS32{8,16,32}R instructions.  and MOVS32I instructions.

gas/ChangeLog:

2023-07-21  Jose E. Marchesi  <jose.marchesi@oracle.com>

	* testsuite/gas/bpf/alu.s: Test movs instructions.
	* testsuite/gas/bpf/alu-pseudoc.s: Likewise.
	* testsuite/gas/bpf/alu32.s: Likewise for movs32 instruction.
	* testsuite/gas/bpf/alu32-pseudoc.s: Likewise.
	* testsuite/gas/bpf/alu.d: Add expected results.
	* testsuite/gas/bpf/alu32.d: Likewise.
	* testsuite/gas/bpf/alu-be.d: Likewise.
	* testsuite/gas/bpf/alu32-be.d: Likewise.
	* testsuite/gas/bpf/alu-pseudoc.d: Likewise.
	* testsuite/gas/bpf/alu32-pseudoc.d: Likewise.
	* testsuite/gas/bpf/alu-be-pseudoc.d: Likewise.
	* testsuite/gas/bpf/alu32-be-pseudoc.d: Likewise.