usb: chipidea: need to mask when writting endptflush and endptprime

usb: chipidea: need to mask when writting endptflush and endptprime

ENDPTFLUSH and ENDPTPRIME registers are set by software and clear
by hardware. There is a bit for each endpoint. When we are setting
a bit for an endpoint we should make sure we do not touch other
endpoint bit. There is a race condition if the hardware clear the
bit between the read and the write in hw_write.

Cc: stable <[email protected]> # 3.11+
Signed-off-by: Peter Chen <[email protected]>
Signed-off-by: Matthieu CASTET <[email protected]>
Tested-by: Michael Grzeschik <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>