Revert "drm: don't associate _DRM_DRIVER maps with a master"

This reverts commit 6c51d1cf, which
apparently causes DRI initialization failures on Radeons.

Reported-by: Markus Trippelsdorf <markus@trippelsdorf.de>
Requested-by: Dave Airlie <airlied@gmail.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>