target/riscv: rename ext_ifencei to ext_zifencei

Add a leading 'z' to improve grepping. When one wants to search for uses
of zifencei they're more likely to do 'grep -i zifencei' than 'grep -i
ifencei'.

Suggested-by: Andrew Jones <ajones@ventanamicro.com>
Signed-off-by: Daniel Henrique Barboza <dbarboza@ventanamicro.com>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Reviewed-by: Andrew Jones <ajones@ventanamicro.com>
Message-ID: <20231012164604.398496-2-dbarboza@ventanamicro.com>
Signed-off-by: Alistair Francis <alistair.francis@wdc.com>

target/riscv/insn_trans/trans_rvi.c.inc

@@ -799,7 +799,7 @@ static bool trans_fence(DisasContext *ctx, arg_fence *a)
 
 static bool trans_fence_i(DisasContext *ctx, arg_fence_i *a)
 {
-    if (!ctx->cfg_ptr->ext_ifencei) {
+    if (!ctx->cfg_ptr->ext_zifencei) {
         return false;
     }