usb: dwc2: gadget: Set TX FIFO depths to calculated defaults

Remove legacy DWC2_G_P_LEGACY_TX_FIFO_SIZE array for TX FIFOs.
Update dwc2_set_param_tx_fifo_sizes function to calculate
and assign default average FIFO depth to each member of
g_tx_fifo_size array. Total FIFO size, EP Info block's size,
FIFO operation mode and device operation mode are taken into
consideration during the calculation.

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>