[committed] [NFC] Fix riscv_init_cumulative_args for unused arguments

[Jeff Law]

The signature was still using ATTRIBUTE_UNUSED and actually marked one 
of the used arguments with ATTRIBUTE_UNUSED.

This patch drops the decorations and instead remove the name of 
arguments which are actually unused which is the preferred way to handle 
this now when we can.

Bootstrapped.  I didn't have test results on the platform where I 
bootstrapped, so no results to compare against.  Given its NFC, I think 
we're OK without the regression results.

Pushed to the trunk.
jeffdiff --git a/gcc/config/riscv/riscv.cc b/gcc/config/riscv/riscv.cc
index 1f9546f4d3e..3ba45ffaa74 100644
--- a/gcc/config/riscv/riscv.cc
+++ b/gcc/config/riscv/riscv.cc
@@ -4873,11 +4873,7 @@ riscv_pass_fpr_pair (machine_mode mode, unsigned regno1,
    For a library call, FNTYPE is 0.  */
 
 void
-riscv_init_cumulative_args (CUMULATIVE_ARGS *cum,
-                           tree fntype ATTRIBUTE_UNUSED,
-                           rtx libname ATTRIBUTE_UNUSED,
-                           tree fndecl ATTRIBUTE_UNUSED,
-                           int caller ATTRIBUTE_UNUSED)
+riscv_init_cumulative_args (CUMULATIVE_ARGS *cum, tree fntype, rtx, tree, int)
 {
   memset (cum, 0, sizeof (*cum));