Sync kernel's unification of jbd2 revoke and tag block checksum handling

Sync kernel's unification of jbd2 revoke and tag block checksum handling

Commit 1101cd4d13ba ("jbd2: unify revoke and tag block checksum
handling") cleans up the fact that the jbd2_journal_revoke_tail and
jbd2_journal_block_tail structures are basically the same.  So it
drops the definition of struct jbd2_journal_revoke_tail and unifies
the functions which calculates and verifies the checksums for revoke
blocks and tag blocks.

Make the same changes in e2fsprogs so eliminate unnecessary
differences in e2fsck/recovery.c and e2fsck/revoke.c.

Signed-off-by: Theodore Ts'o <tytso@mit.edu>