[tlul] Fix "unused" name for AscentLint too

It seems that Verilator is happy to treat foo_unused as a hint that
the signal is unused, but AscentLint requires the name to start with
unused instead.

Signed-off-by: Rupert Swarbrick <rswarbrick@lowrisc.org>

hw/ip/tlul/rtl/tlul_err_resp.sv

diff --git a/hw/ip/tlul/rtl/tlul_err_resp.sv b/hw/ip/tlul/rtl/tlul_err_resp.sv
index 3d082c0..5eb5d41 100644
--- a/hw/ip/tlul/rtl/tlul_err_resp.sv
+++ b/hw/ip/tlul/rtl/tlul_err_resp.sv
@@ -57,7 +57,7 @@
   end
 
   // Waive unused bits of tl_h_i
-  logic tl_h_unused = &{1'b0,
+  logic unused_tl_h = &{1'b0,
                         tl_h_i.a_param, tl_h_i.a_address, tl_h_i.a_mask,
                         tl_h_i.a_data, tl_h_i.a_user, tl_h_i.d_ready};