selftests/bpf: rewrite test_align

Expectations have changed, as has the format of the logged state.
To make the tests easier to read, add a line-matching framework so that
 each match need only quote the register it cares about.  (Multiple
 matches may refer to the same line, but matches must be listed in
 order of increasing line.)
Signed-off-by: Edward Cree <ecree@solarflare.com>
Signed-off-by: David S. Miller <davem@davemloft.net>