staging: r8723au: Add source files for new driver - part 1

The Realtek USB device RTL8723AU is found in Lenovo Yoga 13 tablets.
A driver for it has been available in a GitHub repo for several months.
This commit contains the first part of the source files. The source
is arbitrarily split to avoid E-mail files that are too large.

Jes Sorensen at RedHat has made many improvements to the vendor code,
and he has been doing the testing. I do not have access to this device.

Signed-off-by: Larry Finger <Larry.Finger@lwfinger.net>
Cc: Jes Sorensen <Jes.Sorensen@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>