usb: gadget: mv_udc: rewrite fifo flush

1: Add parameter check.
2: For controller endpoint, we need to flush in and out directions.
3: delete redundant code, make it more readable.

Signed-off-by: Neil Zhang <zhangwm@marvell.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>
1 file changed