[NI] Fix 'only input type' check for intersection types

Check worked incorrectly in case when argument type and expected type are the
same intersection type, which is possible for local variables without explicit
type declaration.

compiler/testData/diagnostics/testsWithStdLib/inference/intersectionInputType.kt

@@ -0,0 +1,12 @@
+// !LANGUAGE: +NewInference
+
+import kotlin.test.assertEquals
+
+fun test() {
+    val u = when (true) {
+        true -> 42
+        else -> 1.0
+    }
+
+    assertEquals(42, u)
+}

compiler/testData/diagnostics/testsWithStdLib/inference/intersectionInputType.txt

@@ -0,0 +1,3 @@
+package
+
+public fun test(): kotlin.Unit