[IR] Allow inline modifier for functions returning MFVC without warning

Signed-off-by: Evgeniy.Zhelenskiy <Evgeniy.Zhelenskiy@jetbrains.com>

#KT-1179

compiler/testData/diagnostics/tests/inline/valueClasses.kt

@@ -0,0 +1,12 @@
+// LANGUAGE: +ValueClasses
+// TARGET_BACKEND: JVM_IR
+// WITH_STDLIB
+// SKIP_TXT
+// FIR_IDENTICAL
+
+@JvmInline
+value class DPoint(val x: Double, val y: Double)
+
+inline fun f1() = DPoint(1.0, 2.0)
+<!NOTHING_TO_INLINE!>inline<!> fun f2() = 2U
+inline val p1 get() = DPoint(1.0, 2.0)