usb: chipidea: udc: zero-length packet is only needed for TX
usb: chipidea: udc: zero-length packet is only needed for TX

The zero-length packet is the sendor tells the receiver that there
is no more data, so it is only needed at the TX side.

Signed-off-by: Peter Chen <c01a8c815a4ad165fff2d1c0d35ddf5b16bd3d7b@freescale.com>

KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs