fs/cramfs: use pr_fmt

Use module name for "cramfs: " prefix.  (note that uncompress.c printk had
no prefix).

Signed-off-by: Fabian Frederick <fabf@skynet.be>
Cc: "Theodore Ts'o" <tytso@mit.edu>
Cc: Sasha Levin <sasha.levin@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>