fix typo in SubmittingPatches

Fix typo.

Signed-off-by: Keiichi Kii <k-keiichi@bx.jp.nec.com>
Cc: Andy Whitcroft <apw@shadowen.org>
Cc: Randy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>