usb: dwc3: Increase the TxFIFO resize factor

With the TxFIFO depth calculated with the current resize
factor, lot of flow control is observed with MTP file
transfer. As a result the file transfer speed is not
meeting the KPIs. Increasing this value so that
flow control is minimized and throughput is improved.

Change-Id: If64c2b6073df12edbcbb75fa08669f5268644e2a
Signed-off-by: Elson Roy Serrao <eserrao@codeaurora.org>