USB: dwc3: gadget: Fix TxFIFO resizing logic

The TxFIFO RAM start address for some USB controller
might be non-zero. The current FIFO resizing logic in
place always considers that this start address is 0x0000
and writes the RAM start address for subsequent TxFIFOs
with the last FIFO depth only, leading to the controller
not functioning properly.

To make the controller work, start address of GTXFIFOSIZ(#n)
should be written with the start address of GTXFIFOSIZ(0)
+ last FIFO depth. Fix the resizing logic accordingly.

Change-Id: Ia83edef7165b980828f2a43832493be2349ae0dc
Signed-off-by: Ajay Agarwal <ajaya@codeaurora.org>