usb: gadget: udc: atmel: fix possible IN hang issue

usb: gadget: udc: atmel: fix possible IN hang issue

commit 6785a1034461c2d2c205215f63a50a740896e55b upstream.

When receive data, the RXRDY in status register set by hardware
after a new packet has been stored in the endpoint FIFO. When it
is copied from FIFO, this bit is cleared which make the FIFO can
be accessed again.

In the receive_data() function, this bit RXRDY has been cleared.
So, after the receive_data() function return, this bit should
not be cleared again, or else it may cause the accessing FIFO
corrupt, which will make the data loss.

Fixes: 914a3f3b3754 (USB: add atmel_usba_udc driver)
Acked-by: Nicolas Ferre <nicolas.ferre@atmel.com>
Signed-off-by: Bo Shen <voice.shen@atmel.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>
[bwh: Backported to 3.2: adjust filename]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>