Return error and prevent from loading module when gss_mech_register()
failed.

Cc: Andy Adamson <andros@citi.umich.edu>
Cc: J. Bruce Fields <bfields@citi.umich.edu>
Acked-by: NTrond Myklebust <Trond.Myklebust@netapp.com>
Signed-off-by: NAkinobu Mita <akinobu.mita@gmail.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>