Remove redundant call to the matroxfb_update_fix() before matrox
frambuffer is registered.

This fixes a problem with uninitialized the fb_info->mm_lock mutex
introduced by the commit 537a1bf0 " fbdev: add mutex for fb_mmap
locking"
Signed-off-by: NKrzysztof Helt <krzysztof.h1@wp.pl>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>