[PATCH] drivers/char/vc_screen.c: proper prototypes

Add proper prototypes for two functions in drivers/char/vc_screen.c

Signed-off-by: Adrian Bunk <bunk@stusta.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>