xhci: Remove references to HC_STATE_RUNNING.

The USB core will set hcd->state to HC_STATE_RUNNING before calling
xhci_run, so there's no point in setting it twice.  The USB core also
doesn't pay attention to HC_STATE_RUNNING on the resume path anymore; it
uses HCD_RH_RUNNING(), which looks at hcd->flags & (1U <<
HCD_FLAG_RH_RUNNING.  Therefore, it's safe to remove the state set in
xhci_bus_resume().

Signed-off-by: Sarah Sharp <sarah.a.sharp@linux.intel.com>