UPSTREAM: dm verity fec: fix bufio leaks

Buffers read through dm_bufio_read() were not released in all code paths.

Fixes: a739ff3f543a ("dm verity: add support for forward error correction")
Cc: stable@vger.kernel.org # v4.5+
Signed-off-by: Sami Tolvanen <samitolvanen@google.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
(cherry picked from commit 86e3e83b443669dd2bcc5c8a83b23e3aa0694c0d)
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>
Change-Id: Id2c35ee727c6d93b37dcd47eeceb49ece086306f
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>