[PATCH] SiS DRM: Fix possible NULL dereference

This fixes a NULL pointer reference in DRM.  The SiS driver tries to
allocate a big chunk of memory, but the return value is never checked.

Reported in Novell bugzilla #132271:
  https://bugzilla.novell.com/show_bug.cgi?id=132271



Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>