dm-verity-fec: warn even when there were no errors

dm-verity-fec: warn even when there were no errors

Currently FEC logs a warning message if at least one error was
corrected, or an error message if there were uncorrectable errors.
However, it doesn't log anything if there were no errors.

"No errors" is actually unexpected, though, considering that dm-verity
calls verity_fec_decode() only when a block's digest doesn't match.

If there were to ever be a bug where verity_fec_decode() is called on
blocks with the correct digest, then there would be no indication in the
log that FEC is running and degrading performance.

Therefore, let's log the warning message even when there were no errors.

Signed-off-by: Eric Biggers <ebiggers@kernel.org>
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>