xhci: remove unnecessary check for pending timer

Checking if the command timeout timer is pending when queueing the
first command to the command ring is not really useful, remove it.

Suggested-by: Lu Baolu <baolu.lu@linux.intel.com>
Signed-off-by: Mathias Nyman <mathias.nyman@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>