bpf: Fix verifier log string check for bad alignment.

The message got changed a lot time ago.

This was responsible for 36 test case failures on sparc64.

Fixes: f1174f77

 ("bpf/verifier: rework value tracking")
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>