ALSA: hda - Pull pages allocation to hda_controller

Pull allocation from first_init to a new function in hda_controller.c.
Short term this will allow the dsp loader to be moved as well.  In
later commits it will allow the same allocation to be used by the
platform hda driver.

Signed-off-by: Dylan Reid <dgreid@chromium.org>
Signed-off-by: Takashi Iwai <tiwai@suse.de>