jffs2: Fix typo in compr.c

Correct spelling "modul" to "module" in
fs/hffs2/compr.c

Signed-off-by: Masanari Iida <standby24x7@gmail.com>
Signed-off-by: Artem Bityutskiy <artem.bityutskiy@linux.intel.com>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>