use PinMatrixRequestType instead of arbitrary string

protob/messages.proto

@@ -142,7 +142,7 @@ message ButtonAck {
 //
 // Response: PinMatrixAck, Cancel
 message PinMatrixRequest {
-	optional string message = 1;	// Human readable message
+	optional PinMatrixRequestType type = 1;
 }
 
 // Message is sent by the computer as a response to PinMatrixRequest previously sent by the device.

protob/types.proto

@@ -57,6 +57,12 @@ enum ButtonRequestType {
 	ButtonRequest_SignTx = 8;
 }
 
+enum PinMatrixRequestType {
+	PinMatrixRequestType_Current = 1;
+	PinMatrixRequestType_NewFirst = 2;
+	PinMatrixRequestType_NewSecond = 3;
+}
+
 // Structure of BIP32 (hierarchical deterministic) node
 // Used for imports of private key into the device and exporting public key out of device
 message HDNodeType {