s390/bpf,jit: add support for BPF_S_ANC_ALU_XOR_X instruction

Add support for new BPF_S_ANC_ALU_XOR_X instruction which got added
with ffe06c17 "filter: add XOR operation".

s390 version of 4bfaddf1 "x86 bpf_jit: support BPF_S_ANC_ALU_XOR_X instruction".

Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>