[mono][interp] Remove redundant check

If we are calling a method of a valuetype, then we already know `this` pointer is an instantiation of a valuetype.

Author: BrzVlad

src/mono/mono/mini/interp/interp.c

@@ -4003,7 +4003,7 @@ mono_interp_exec_method (InterpFrame *frame, ThreadContext *context, FrameClause
 					MonoObject *this_arg = del->target;
 
 					// replace the MonoDelegate* on the stack with 'this' pointer
-					if (m_class_is_valuetype (this_arg->vtable->klass) && m_class_is_valuetype (cmethod->method->klass)) {
+					if (m_class_is_valuetype (cmethod->method->klass)) {
 						gpointer unboxed = mono_object_unbox_internal (this_arg);
 						LOCAL_VAR (call_args_offset, gpointer) = unboxed;
 					} else {
@@ -4103,7 +4103,7 @@ mono_interp_exec_method (InterpFrame *frame, ThreadContext *context, FrameClause
 			ip += 5;
 			// FIXME push/pop LMF
 			cmethod = get_virtual_method_fast (cmethod, this_arg->vtable, slot);
-			if (m_class_is_valuetype (this_arg->vtable->klass) && m_class_is_valuetype (cmethod->method->klass)) {
+			if (m_class_is_valuetype (cmethod->method->klass)) {
 				/* unbox */
 				gpointer unboxed = mono_object_unbox_internal (this_arg);
 				LOCAL_VAR (call_args_offset, gpointer) = unboxed;