s390/bpf: Implement unconditional byte swap

Implement the cpuv4 unconditional byte swap, which is encoded as
BPF_ALU64 | BPF_END | BPF_FROM_LE. Since s390x is big-endian, it's
the same as the existing BPF_ALU | BPF_END | BPF_FROM_LE.
Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>
Link: https://lore.kernel.org/r/20230919101336.2223655-7-iii@linux.ibm.comSigned-off-by: Alexei Starovoitov <ast@kernel.org>

arch/s390/net/bpf_jit_comp.c

@@ -1253,6 +1253,7 @@ static noinline int bpf_jit_insn(struct bpf_jit *jit, struct bpf_prog *fp,
 		}
 		break;
 	case BPF_ALU | BPF_END | BPF_FROM_LE:
+	case BPF_ALU64 | BPF_END | BPF_FROM_LE:
 		switch (imm) {
 		case 16: /* dst = (u16) cpu_to_le16(dst) */
 			/* lrvr %dst,%dst */