ppc: bpf: implement jitting of JMP32

This patch implements code-gen for new JMP32 instructions on ppc.

For JMP32 | JSET, instruction encoding for PPC_RLWINM_DOT is added to check
the result of ANDing low 32-bit of operands.

Cc: Naveen N. Rao <naveen.n.rao@linux.ibm.com>
Cc: Sandipan Das <sandipan@linux.ibm.com>
Signed-off-by: Jiong Wang <jiong.wang@netronome.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>