arm/dt: msm8974: Set USB3 BAM DATA FIFO size as 6KB

QDSS BAM which communicates with USB BAM in BAM to BAM mode
has hardware issues which requires DATA FIFO size to be 6KB
in order to avoid deadlock or data stalls.

Change-Id: If935520d569271e2f5f8907c4aecf5fcf75c49b0
Signed-off-by: Manu Gautam <mgautam@codeaurora.org>