[platform] Fixed return code processing in set_low_power_mode() for B…

…FN platform (#3610)

Signed-off-by: Andriy Kokhan <[email protected]>

device/barefoot/x86_64-accton_wedge100bf_32x-r0/plugins/sfputil.py

@@ -135,7 +135,7 @@ def set_low_power_mode(self, port_num, lpmode):
         self.thrift_setup()
         status = pltfm_mgr.pltfm_mgr_qsfp_lpmode_set(port_num, lpmode)
         self.thrift_teardown()
-        return status
+        return (status == 0)
 
     def reset(self, port_num):
         # Check for invalid port_num