chipsfb: use correct pm state

chipsfb.c shouldn't use PM_SUSPEND_MEM in there, but PM_EVENT_SUSPEND.

Cc: Cedric Le Goater <clg@fr.ibm.com>
Cc: "Antonino A. Daplas" <adaplas@pol.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>