usb: gadget: zynq: Clear each endpoint status instead of all the endpoints

Clear each endpoint status instead of the status read at the beginning of the
handler which indicates complete status of all endpoints.

Signed-off-by: Punnaiah Choudary Kalluri <punnaia@xilinx.com>
Signed-off-by: Michal Simek <michal.simek@xilinx.com>