ps3fb: make ps3fb_wait_for_vsync() and ps3fb_flip_ctl() static

Make ps3fb_wait_for_vsync() and ps3fb_flip_ctl() static, as they're no
(longer) used outside ps3fb.

Signed-off-by: Geert Uytterhoeven <Geert.Uytterhoeven@sonycom.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>