ASoC: msm: Add support for 24-bit playback

Update MSM ALSA driver to support 24-bit PCM sample packed into 32-bit
frame. A mixer control is added to allow 24/16 bitwidth selection on
SLIMBUS_0_RX backend

Change-Id: Ib2530159841bf191d4b27d0750db4c4a191bc0e0
Signed-off-by: Bhalchandra Gajare <gajare@codeaurora.org>