nfp: bpf: fix check of program max insn count

NFP program allocation length is in bytes and NFP program length
is in instructions, fix the comparison of the two.

Fixes: 9314c442

 ("nfp: bpf: move translation prepare to offload.c")
Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Reviewed-by: Jiong Wang <jiong.wang@netronome.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>