USB: host: whci: rename Kbuild file

We have been using Makefile for well over a decade now, use that name
instead of Kbuild.

Also, while moving the file, add the proper SPDX identifier at the top
of it.

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

drivers/usb/host/whci/Makefile

@@ -1,3 +1,5 @@
+# SPDX-License-Identifier: GPL-2.0
+
 obj-$(CONFIG_USB_WHCI_HCD) += whci-hcd.o
 
 whci-hcd-y := \