powerpc/bpf: Remove redundant check for non-null image

We have a check earlier to ensure we don't proceed if image is NULL. As
such, the redundant check can be removed.

Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
[Added similar changes for classic BPF JIT]
Signed-off-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>