usb: gadget: mv_udc: fix bug when handle setup package.

For the code doesn't restrict controller ep must be ep0, so we will go
through all the eps and check if there is a setup package received.
And also we just need to acknowledge the corresponding bit in
ENDPTSETUPSTAT register.

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