target/riscv: Remove exit_tb and lookup_and_goto_ptr

GDB single-stepping is now handled generically, which means
we don't need to do anything in the wrappers.

Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>

target/riscv/insn_trans/trans_rvv.c.inc

@@ -41,7 +41,7 @@ static bool trans_vsetvl(DisasContext *ctx, arg_vsetvl *a)
     gen_set_gpr(ctx, a->rd, dst);
 
     tcg_gen_movi_tl(cpu_pc, ctx->pc_succ_insn);
-    lookup_and_goto_ptr(ctx);
+    tcg_gen_lookup_and_goto_ptr();
     ctx->base.is_jmp = DISAS_NORETURN;
     return true;
 }