"Let type implement interface": don't suggest same type #KT-25928 Fixed

idea/testData/quickfix/typeMismatch/kt25928.kt

@@ -0,0 +1,9 @@
+// "Let 'Foo?' extend interface 'Foo'" "false"
+// ACTION: Add non-null asserted (!!) call
+// ACTION: Change type of 'x' to 'Foo?'
+// ERROR: Type mismatch: inferred type is Foo? but Foo was expected
+interface Foo
+
+fun test(foo: Foo?) {
+    val x: Foo = foo<caret>
+}