LinuxDevice: Added supported eabi property.

Added property to linux device to return list of supported abis
to be consistent with android devices. Currently only returns a
list containing the primary abi.

wlauto/common/linux/device.py

@@ -136,6 +136,10 @@ class BaseLinuxDevice(Device):  # pylint: disable=abstract-method
                 self._abi = val
         return self._abi
 
+    @property
+    def supported_abi(self):
+        return [self.abi]
+
     @property
     def online_cpus(self):
         val = self.get_sysfile_value('/sys/devices/system/cpu/online')