We used a on-demand i915 component binding for IvyBridge and
SandyBridge HDMI codecs, but it has a potential problem of the nested
module loading.  For avoiding that situation, assure the i915 binding
happening at the controller driver level for PCH controller devices,
where the initialization is performed in a detached work, instead of
calling from the codec driver probe.
Signed-off-by: Takashi Iwai <tiwai@suse.de>