ALSA: aloop - Use vmalloc buffer

ALSA: aloop - Use vmalloc buffer

BZ: 30009

This patch is back ported ICS kernel from k3.2 rc1

snd-aloop driver is virtual and has no need for allocating contiguous
pages.  It'll be more system-friendly to use vmalloc buffers.

Change-Id: I8cc6901f38706daa5cb1dfbddb34cc6b648236da
Tested-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Ramesh Babu K V <ramesh.babu@linux.intel.com>
Reviewed-on: http://android.intel.com:8080/42441
Reviewed-by: Babu, Ramesh <ramesh.babu@intel.com>
Reviewed-by: Koul, Vinod <vinod.koul@intel.com>
Reviewed-by: Abdullah, Omair M <omair.m.abdullah@intel.com>
Reviewed-by: Agarwal, Vaibhav <vaibhav.agarwal@intel.com>
Reviewed-by: Balguri, Mamatha <mamatha.balguri@intel.com>
Reviewed-by: Gupta, ArvindX K <arvindx.k.gupta@intel.com>
Reviewed-by: Hibare, PramodX <pramodx.hibare@intel.com>
Tested-by: Hibare, PramodX <pramodx.hibare@intel.com>
Reviewed-by: buildbot <buildbot@intel.com>
Tested-by: buildbot <buildbot@intel.com>