supplicant(interface): Correct the WFD info length

Error logs from test:
03-17 18:34:34.303  1781  1781 E wpa_supplicant: Unexpected WFD device
info len: 6

Bug: 36401779
Test: Compiles
Change-Id: I65805599f8f3242a5c1f6ba8c0a1b9da05df79b4
diff --git a/wifi/supplicant/1.0/ISupplicantP2pIfaceCallback.hal b/wifi/supplicant/1.0/ISupplicantP2pIfaceCallback.hal
index b6ee57f..8a54bf4 100644
--- a/wifi/supplicant/1.0/ISupplicantP2pIfaceCallback.hal
+++ b/wifi/supplicant/1.0/ISupplicantP2pIfaceCallback.hal
@@ -105,7 +105,7 @@
       MacAddress srcAddress, MacAddress p2pDeviceAddress,
       uint8_t[8] primaryDeviceType, string deviceName,
       bitfield<WpsConfigMethods> configMethods, uint8_t deviceCapabilities,
-      bitfield<P2pGroupCapabilityMask> groupCapabilities, uint8_t[8] wfdDeviceInfo);
+      bitfield<P2pGroupCapabilityMask> groupCapabilities, uint8_t[6] wfdDeviceInfo);
 
   /**
    * Used to indicate that a P2P device has been lost.