Section 4.4.7.2 "Interrupt Transfer Bandwidth Requirements" of the USB3.0 spec
says:
	A zero-length data payload is a valid transfer and may be useful for
	some implementations.

So, extend the logic of allowing URB_ZERO_PACKET to interrupt urbs too.
Otherwise, the kernel throws warning of BOGUS transfer flags.
Signed-off-by: NAmit Virdi <amit.virdi@st.com>
Acked-by: NHans de Goede <hdegoede@redhat.com>
Acked-by: NAlan Stern <stern@rowland.harvard.edu>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>