Instead of not even having the test functions if network tests are disabled, use
a custom decorator to mark the network tests and skip them.
(Bitbake rev: cc420f430b1dafd9ca944bea259a564aaab34595)
Signed-off-by: Ross Burton <ross.burton@intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>