xHCI: prolong host controller halt time limit

xHCI 1.0 spec specifies the xHC shall halt within 16ms after software clears
Run/Stop bit. In xHCI 0.96 spec the time limit is 16 microframes (2ms), it's
too short and often cause dmesg shows "Host controller not halted, aborting
reset." message when rmmod xhci-hcd.

Modify the time limit to comply with xHCI 1.0 specification and prevents the
warning message showing when remove xhci-hcd.

Signed-off-by: Andiry Xu <andiry.xu@amd.com>
Signed-off-by: Sarah Sharp <sarah.a.sharp@linux.intel.com>