[NI] Fix coercion to Unit for explicitly specified type argument

#KT-25424 Fixed

compiler/testData/diagnostics/tests/inference/coercionToUnit/coercionWithExplicitTypeArgument.kt

@@ -0,0 +1,10 @@
+// !LANGUAGE: +NewInference
+// !DIAGNOSTICS: -UNUSED_EXPRESSION -UNUSED_VARIABLE
+
+fun foo() {
+    val f = myRun<Unit> {
+        123
+    }
+}
+
+fun <R> myRun(block: () -> R): R = block()

compiler/testData/diagnostics/tests/inference/coercionToUnit/coercionWithExplicitTypeArgument.txt

@@ -0,0 +1,4 @@
+package
+
+public fun foo(): kotlin.Unit
+public fun </*0*/ R> myRun(/*0*/ block: () -> R): R