s390: bpf: implement jitting of BPF_ALU | BPF_ARSH | BPF_*

This patch implements code-gen for BPF_ALU | BPF_ARSH | BPF_*.

Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Jiong Wang <jiong.wang@netronome.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>