powerpc/ppc-opcode: Consolidate powerpc instructions from bpf_jit.h

Move macro definitions of powerpc instructions from bpf_jit.h to
ppc-opcode.h and adopt the users of the macros accordingly. `PPC_MR()`
is defined twice in bpf_jit.h, remove the duplicate one.

Signed-off-by: Balamuruhan S <bala24@linux.ibm.com>
Tested-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
Acked-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
Acked-by: Sandipan Das <sandipan@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200624113038.908074-5-bala24@linux.ibm.com