staging: rtl8723au: The 8723 only has two paths

Converting the driver from the original RTL provided version, by error
converted the code to use four, which caused all sorts of issues. The
confusion was caused by the RTL driver having support for both two and
four paths, and in some places had RF_PATH_MAX = 3. At the same time
it kept the data structures hard coded for two paths, in particular
the ones matching the efuse data.

Signed-off-by: Jes Sorensen <Jes.Sorensen@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>