usb: host: xhci-plat: sort the headers in alphabetic order

Sorting the headers in alphabetic order will help to reduce the conflict
when adding new headers later.

Signed-off-by: Gregory CLEMENT <gregory.clement@free-electrons.com>
Acked-by: Felipe Balbi <balbi@ti.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>