Fix implicit cast of enum-type

store_req_t is a parameter coming from above, it contains tag_mode_e.
This leads to an error in slang flagging the implicit cast:
> error: no implicit conversion from 'bit[0:0]' to 'tag_mode_e';
> explicit conversion exists, are you missing a cast?

If we just assign a casted zero-vector this is prevented.

Author: phsauter

src/hit_miss_detect/axi_llc_tag_store.sv

@@ -255,7 +255,7 @@ module axi_llc_tag_store #(
     end
   end
 
-  `FFLARN(req_q, req_i, load_req, store_req_t'{default: '0}, clk_i, rst_ni)
+  `FFLARN(req_q, req_i, load_req, store_req_t'(0), clk_i, rst_ni)
   `FFLARN(busy_q, busy_d, switch_busy, 1'b0, clk_i, rst_ni)
   assign busy_d = ~busy_q;
   `FFLARN(ram_rvalid_q, ram_rvalid_d, lock_rvalid, way_ind_t'(0), clk_i, rst_ni)