mtp: Address clang compilation errors

* Move default value of debug_enabled to declaration
* Set more-correct fake values for MtpProperty sets

Change-Id: Ife3c15ac6c908848c16a609e8e505336e53c19d8
diff --git a/mtp/mtp_MtpDatabase.cpp b/mtp/mtp_MtpDatabase.cpp
index 17053f1..5eb7d8e 100755
--- a/mtp/mtp_MtpDatabase.cpp
+++ b/mtp/mtp_MtpDatabase.cpp
@@ -836,8 +836,8 @@
 
 			// get current value
 			// TODO: add actual values
-			result->setCurrentValue('\0');
-			result->setDefaultValue('\0');
+			result->setCurrentValue(0);
+			result->setDefaultValue(0);
 			break;
 		}