usb: host: xhci-plat: improve the comments for xhci_plat_suspend

To reflect the current code status.

Signed-off-by: Peter Chen <peter.chen@nxp.com>
Signed-off-by: Mathias Nyman <mathias.nyman@linux.intel.com>
Link: https://lore.kernel.org/r/20200918131752.16488-7-mathias.nyman@linux.intel.com


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>