Increase XHCI suspend timeout to 16ms

The Intel XHCI specification says that after clearing the run/stop bit
the controller may take up to 16ms to halt. We've seen a device take
14ms, which with the current timeout of 10ms causes the kernel to
abort the suspend. Increasing the timeout to the recommended value
fixes the problem.

This patch should be backported to kernels as old as 2.6.37, that
contain the commit 5535b1d5 "USB: xHCI:
PCI power management implementation".

Signed-off-by: Michael Spang <spang@chromium.org>
Signed-off-by: Sarah Sharp <sarah.a.sharp@linux.intel.com>
Cc: stable@vger.kernel.org