powerpc/bpf: Move bpf_jit64.h into bpf_jit_comp64.c

There is no need for a separate header anymore. Move the contents of
bpf_jit64.h into bpf_jit_comp64.c

Signed-off-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/b873a8e6eff7d91bf2a2cabdd53082aadfe20761.1644834730.git.naveen.n.rao@linux.vnet.ibm.com