Fix storybook toggleMax stub.

Author: valentinewallace

stories/screen-story.js

@@ -107,7 +107,7 @@ sinon.stub(invoice, 'generateUri');
 const payment = new PaymentAction(store, grpc, nav, notify);
 sinon.stub(payment, 'checkType');
 sinon.stub(payment, 'payBitcoin');
-sinon.stub(payment, 'setMax');
+sinon.stub(payment, 'toggleMax');
 sinon.stub(payment, 'payLightning');
 sinon.stub(payment, 'initPayBitcoinConfirm');
 const channel = new ChannelAction(store, grpc, nav, notify);