[FIR] Fix conversion of underscored value parameters in functions

Fix false REDECLARATION

compiler/testData/diagnostics/tests/redeclarations/RedeclaredValueParameters.fir.kt

@@ -4,4 +4,6 @@ fun test2(block: (Int, String) -> Unit) { }
 
 fun main() {
     test2 { <!REDECLARATION!>b<!>, <!REDECLARATION!>b<!> -> ; }
+
+    val func: (Int, Int) -> Int = fun(_, _): Int { return 42 }
 }

compiler/testData/diagnostics/tests/redeclarations/RedeclaredValueParameters.kt

@@ -4,4 +4,6 @@ fun test2(block: (Int, String) -> Unit) { }
 
 fun main() {
     test2 { <!REDECLARATION, REDECLARATION!>b<!>, <!REDECLARATION, REDECLARATION!>b<!> -> ; }
+
+    val func: (Int, Int) -> Int = fun(_, _): Int { return 42 }
 }