xHCI: fix cycle bit set in giveback_first_trb()

giveback_first_trb() controls the cycle bit set of the start_trb, to ensure
that the start_trb is written last and the host controller will receive a
whole td at a time.

However, if the ring is wrapped and cycle bit is toggled to zero, then
giveback_first_trb() will be of no effect. In this case, set the cycle bit of
start_trb to 1 at the beginning and clear it in giveback_first_trb().

Signed-off-by: Andiry Xu <andiry.xu@amd.com>
Signed-off-by: Sarah Sharp <sarah.a.sharp@linux.intel.com>