usb_bam: Remove support for USB3 internal memory as BAM FIFOs

Earlier USB3 controller's internal memory was used BAM FIFO for
QDSS pipe. As there is now dedicated chunk in OCIMEM assigned
to support the same, drop support for using USB3 private memory.

Change-Id: Ic2ffb6c1f8589e57e06f1e72560fcb49e5a9511a
Signed-off-by: Manu Gautam <mgautam@codeaurora.org>