USB: xHCI: Supporting MSI/MSI-X

Enable MSI/MSI-X supporting in xhci driver.

Provide the mechanism to fall back using MSI and Legacy IRQs
if MSI-X IRQs register failed.

Signed-off-by: Dong Nguyen <Dong.Nguyen@amd.com>
Signed-off-by: Sarah Sharp <sarah.a.sharp@linux.intel.com>,
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

diff --cc drivers/usb/core/hcd.c
Simple merge

diff --cc drivers/usb/host/xhci.c
Simple merge

diff --cc drivers/usb/host/xhci.h
Simple merge