Staging: most: add MOST driver's aim-sound module

This patch adds the aim-sound module of the MOST driver to the kernel's
driver staging area. This module is part of the MOST driver and handles
user space interaction by means of ALSA devices.

This patch is needed in order to have access to MOST synchronous data
through ALSA devices.

Signed-off-by: Christian Gromm <christian.gromm@microchip.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>