staging: Hook the DWC2 driver into the build system

Add the DWC2 Kconfig and Makefile, and modify the staging Kconfig and
Makefile to include them

Signed-off-by: Paul Zimmerman <paulz@synopsys.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
4 files changed