drm: Use a normal idr allocation for the obj->name

drm: Use a normal idr allocation for the obj->name

Unlike the handle, the name table uses a sleeping mutex rather than a
spinlock. The allocation is in a normal context, and we can use the
simpler sleeping gfp_t, rather than have to take from the atomic
reserves.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1451902261-25380-3-git-send-email-chris@chris-wilson.co.uk
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>