USB: core: use kernel assigned address for devices under xHCI

xHCI driver uses hardware assigned device address. This may cause device
address conflict in certain cases.

Use kernel assigned address for devices under xHCI. Store the xHC assigned
address locally in xHCI driver.

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