msm: mpq8064: Allow client to select num bufs for VC to hold onto

VC part of the VCAP driver was initial implmented for the hardware
to 2 store and work with 2 buffers. Since hardware is capable of
storing and filling up to 6 buffers, a new API was created to allow
client to select how many they want VC to use.

Change-Id: I0548f1322c9703d9ccf12700be05511b0e1eb0de
Signed-off-by: Terence Hampson <thampson@codeaurora.org>