bpf: gas,include,opcode: add suppor for instructions BSWAP{16,32,64}

bpf: gas,include,opcode: add suppor for instructions BSWAP{16,32,64}

This patch adds support for the BPF V4 ISA byte swap instructions to
opcodes, assembler and disassembler.

Tested in bpf-unknown-none.

include/ChangeLog:

2023-07-24  Jose E. Marchesi  <jose.marchesi@oracle.com>

	* opcode/bpf.h (BPF_IMM32_BSWAP16): Define.
	(BPF_IMM32_BSWAP32): Likewise.
	(BPF_IMM32_BSWAP64): Likewise.
	(enum bpf_insn_id): New entries BPF_INSN_BSWAP{16,32,64}.

opcodes/ChangeLog:

2023-07-24  Jose E. Marchesi  <jose.marchesi@oracle.com>

	* bpf-opc.c (bpf_opcodes): Add entries for the BSWAP*
	instructions.

gas/ChangeLog:

2023-07-24  Jose E. Marchesi  <jose.marchesi@oracle.com>

	* doc/c-bpf.texi (BPF Instructions): Document BSWAP* instructions.
	* testsuite/gas/bpf/alu.s: Test BSWAP{16,32,64} instructions.
	* testsuite/gas/bpf/alu.d: Likewise.
	* testsuite/gas/bpf/alu-be.d: Likewise.
	* testsuite/gas/bpf/alu-pseudoc.s: Likewise.
	* testsuite/gas/bpf/alu-pseudoc.d: Likewise.
	* testsuite/gas/bpf/alu-be-pseudoc.d: Likewise.