bpf: fix register NEG[32] instructions

This patch fixes the BPF_INSN_NEGR and BPF_INSN_NEG32R BPF
instructions to not use their source registers.

Tested in bpf-unknown-none.

opcodes/ChangeLog:

2023-07-26  Jose E. Marchesi  <jose.marchesi@oracle.com>

	* bpf-opc.c (bpf_opcodes): Fix BPF_INSN_NEGR to not use a src
	register.

gas/ChangeLog:

2023-07-26  Jose E. Marchesi  <jose.marchesi@oracle.com>

	* testsuite/gas/bpf/alu.s: The register neg instruction gets only
	one argument.
	* testsuite/gas/bpf/alu32-be-pseudoc.d: Likewise.
	* testsuite/gas/bpf/alu32-pseudoc.d: Likewise.
	* testsuite/gas/bpf/alu32-pseudoc.s: Likewise.
	* testsuite/gas/bpf/alu-pseudoc.d: Likewise.
	* testsuite/gas/bpf/alu-be-pseudoc.d: Likewise.
	* testsuite/gas/bpf/alu-pseudoc.s: Likewise.
	* testsuite/gas/bpf/alu-be.d: Likewise.
	* testsuite/gas/bpf/alu.d: Likewise.
	* testsuite/gas/bpf/alu32-be.d: Likewise.
	* testsuite/gas/bpf/alu32.d: Likewise.
	* testsuite/gas/bpf/alu32.s: Likewise.
	* doc/c-bpf.texi (BPF Instructions): Update accordingly.