usb: dwc3: debugfs: Print eps Tx/RxFIFO in bytes

TxFIFO and RxFIFO from GDBGFIFOSPACE are fifo depths in MDWIDTH. Convert
them into bytes for easier read.

Signed-off-by: Thinh Nguyen <thinhn@synopsys.com>
Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>