xhci: Fix a logical vs bitwise AND bug

The intent was to test whether the flag was set.

This patch should be backported to stable kernels as old as 3.0, since
it fixes a bug in commit e95829f4 "xhci:
Switch PPT ports to EHCI on shutdown.", which was marked for stable.

Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Sarah Sharp <sarah.a.sharp@linux.intel.com>
Cc: stable@vger.kernel.org