Remove unnecessary check in drivers/video/intelfb/intelfbhw.c

All callers and the function itself dereference dinfo, so we can remove the
check.  (coverity id #1371)

Signed-off-by: Eric Sesterhenn <snakebyte@gmx.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Dave Airlie <airlied@linux.ie>