Moving the DSP loading functionality to hda_controller.c means that
the dsp lock doesn't need to be shared in hda_intel and
hda_controller.  The forthcoming platform driver doesn't need the DSP
loading code, but sharing it doesn't hurt.

Tested on Chromebook Pixel's ca0132 that uses the DSP loader.
Signed-off-by: Dylan Reid <dgreid@chromium.org>
Signed-off-by: Takashi Iwai <tiwai@suse.de>