v2: added amount to discount

Signed-off-by: nfel <nfilsaraee@gmail.com>

wallet/v1/msg.proto

@@ -492,6 +492,7 @@ message LockAssetReq {
 message AssetDiscountReq {
   string code = 1;
   string asset_id = 2;
+  optional double amount = 3; // calculate discount amount
 }
 
 message AssetDiscountRes {
@@ -499,4 +500,5 @@ message AssetDiscountRes {
   string expires_at = 2;
   double static_amount = 3;
   double percentage = 4;
+  optional double discount_amount = 5; // based of asset price and discount amount in req
 }