drm: Release resources with a safer function

We should use 'ida_simple_remove()' instead of 'ida_remove()' when freeing
resources allocated with 'ida_simple_get()'.

Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: http://patchwork.freedesktop.org/patch/msgid/1475825261-7735-1-git-send-email-christophe.jaillet@wanadoo.fr