ASoC: msm: Flexible period size for pcm playback

PCM driver was configured for fixed buffer
size on the playback path. With this, varying
the buffer sizes on the playback path was not
possible. To fix this, support for flexible
period sizes is added by setting different
values for min and max buffer sizes

Change-Id: I7f69db4940f67e5e3a795101af1b1682afbdb530
Signed-off-by: Alexy Joseph <alexyj@codeaurora.org>
Signed-off-by: Mekala Natarajan <mekalan@codeaurora.org>