drivers/video/via/viafbdev.c: fix oops with no /proc

Fixed a typo: missing *.  This would lead to a kernel oops if the kernel
was compiled without support for the /proc file system.

Found with a static checker.  Compile tested.

Signed-off-by: Dan Carpenter <error27@gmail.com>
Acked-by: Florian Tobias Schandinat <FlorianSchandinat@gmx.de>
Cc: Joseph Chan <JosephChan@via.com.tw>
Cc: Scott Fang <ScottFang@viatech.com.cn>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>