Fix disabled amount inputs when no available quotes

This is a bug. The amount inputs should not remain disabled when max
quote requests return no quote results.

Author: samholmes

src/components/scenes/RampCreateScene.tsx

@@ -616,10 +616,11 @@ export const RampCreateScene: React.FC<Props> = (props: Props) => {
   }
 
   const fiatInputDisabled =
-    'max' in exchangeAmount || amountTypeSupport.onlyCrypto
+    ('max' in exchangeAmount && sortedQuotes.length > 0) ||
+    amountTypeSupport.onlyCrypto
   const cryptoInputDisabled =
     isLoadingPersistedCryptoSelection ||
-    'max' in exchangeAmount ||
+    ('max' in exchangeAmount && sortedQuotes.length > 0) ||
     amountTypeSupport.onlyFiat
 
   // Render trade form view