ASoC:msm: Increase Proxy buffering

-Proxy buffering can overflow if BT
playback setup takes a lot of time
-Fix this by increasing the proxy
buffer size so that we will end
up buffering the additional data that
can come in during this time

Change-Id: I736937ad03684a3b9aff586b8f676ec60259a442
Signed-off-by: Alexy Joseph <alexyj@codeaurora.org>