thunderbolt: Fix xhci check in usb4_switch_setup()

thunderbolt: Fix xhci check in usb4_switch_setup()

The code tried to check whether xhci variable has ROUTER_CS_6_HCI bit
set but since xhci type is bool and it already holds true or false based
on that very bit, fix the check to use the variable directly.

Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Fixes: b04079837b20 ("thunderbolt: Add initial support for USB4")
Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Link: https://lore.kernel.org/r/20200108125317.36444-2-mika.westerberg@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>