usb: dwc2: gadget: Add checking for g-tx-fifo-size parameter

Add dwc2_check_param_tx_fifo_sizes function which validates
the members of g_tx_fifo_size array and sets to average or
default values if it is needed.

Cc: Stefan Wahren <stefan.wahren@i2se.com>
Signed-off-by: Sevak Arakelyan <sevaka@synopsys.com>
Signed-off-by: John Youn <johnyoun@synopsys.com>
Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>