Simplify lit test. use more descriptive name.

Author: navyxliu

mlir/test/Transforms/remove-dead-values.mlir

@@ -569,21 +569,16 @@ module @return_void_with_unused_argument {
     call @fn_return_void_with_unused_argument(%arg0, %unused) : (i32, memref<4xi32>) -> ()
     return %unused : memref<4xi32>
   }
-  // the function is immutable because it is public.
-  func.func public @immutable_fn_return_void_with_unused_argument(%arg0: i32, %unused: i32) -> () {
-    %sum = arith.addi %arg0, %arg0 : i32
-    %c0 = arith.constant 0 : index
-    %buf = memref.alloc() : memref<1xi32>
-    memref.store %sum, %buf[%c0] : memref<1xi32>
+  // the function signature is immutable because it is public.
+  func.func public @public_fn_with_unused_argument(%unused: i32) -> () {
     return
   }
   // CHECK-LABEL: func.func @main2
-  // CHECK-SAME: (%[[ARG0_MAIN:.*]]: i32)
   // CHECK: %[[UNUSED:.*]] = arith.constant 0 : i32
-  // CHECK: call @immutable_fn_return_void_with_unused_argument(%[[ARG0_MAIN]], %[[UNUSED]]) : (i32, i32) -> ()
+  // CHECK: call @public_fn_with_unused_argument(%[[UNUSED]]) : (i32) -> ()
   func.func @main2(%arg0: i32) -> () {
     %zero = arith.constant 0 : i32
-    call @immutable_fn_return_void_with_unused_argument(%arg0, %zero) : (i32, i32) -> ()
+    call @public_fn_with_unused_argument(%zero) : (i32) -> ()
     return
   }
 }