[NAN] Do not expose WifiManager.isNanSupported as new API

The WifiManager.isXxxSupported() only functions if HAL is enabled
and seems to be a duplicate of:

PackageManager.hasSystemFeature(PackageManager.FEATURE_WIFI_NAN)

Bug: 28251988
Change-Id: I8f410def6f0bd3d3fc0926072ab66acce52a0e14
1 file changed