drm: Mark set/drop master ioctl as unlocked.

drm: Mark set/drop master ioctl as unlocked.

Again this is neatly protected by the dev->master_mutex now. There is
a driver callback both for set and drop, but it's only used by vmwgfx.
And vmwgfx has it's own solid locking for shared resources (besides
dev->master_mutex), hence is all safe. Let's drop another place where
the drm legacy bkl is used.

Cc: Chris Wilson <[email protected]>
Reviewed-by: Chris Wilson <[email protected]>
Reviewed-by: Emil Velikov <[email protected]>
Signed-off-by: Daniel Vetter <[email protected]>
Link: http://patchwork.freedesktop.org/patch/msgid/[email protected]