msm: board-8064: Increase MFC ION heap size by 256KB

In order to support extra data during secure playback,
video core meta data buffers need to be allocated from
MFC heap. This is required as both HLOS and video core
have read-write access to this heap. As each meta buffer
size is 8KB and there can be 32 meta & output buffers,
increase the MFC ION heap size by  256KB.

Change-Id: I1e9b5b0329d1f2566c156417b06b2c66fa4e98cc
Signed-off-by: Rajeshwar Kurapaty <rkurapat@codeaurora.org>