[FIR] KT-57655: Add the missing branch

^KT-57655 Fixed

compiler/testData/diagnostics/tests/unsignedTypes/conversions/implicitIntegerCoercionNamedArg.kt

@@ -0,0 +1,21 @@
+// FIR_IDENTICAL
+// ISSUE: KT-57655
+// !LANGUAGE: +ImplicitSignedToUnsignedIntegerConversion
+// ALLOW_KOTLIN_PACKAGE
+
+// FILE: annotation.kt
+
+package kotlin.internal
+
+annotation class ImplicitIntegerCoercion
+
+// FILE: test.kt
+
+import kotlin.internal.ImplicitIntegerCoercion
+
+fun test(@ImplicitIntegerCoercion x: UInt) = x
+
+fun main() {
+    println(test(x = 5))
+    println(test(5))
+}