usb: dwc3: enforce hardware restriction on TRB size

Perform sanity check on the TRB size, to ensure
that it complies with the hardware restriction
of 8KB for dbm TRB.

Change-Id: Idb4081dfa54ea884773fbb4011345aae19f7e133
CRs-Fixed: 565661
Signed-off-by: Dov Levenglick <dovl@codeaurora.org>