disas/riscv: Fix vsetivli disassembly

The first immediate field is unsigned, whereas operand_vimm
extracts a signed value.  There is no need to mask the result
with 'u'; just print the immediate with 'i'.

Fixes: 07f4964d178 ("disas/riscv.c: rvv: Add disas support for vector instructions")
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Reviewed-by: Pierrick Bouvier <pierrick.bouvier@linaro.org>
Reviewed-by: LIU Zhiwei <zhiwei_liu@linux.alibaba.com>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>

disas/riscv.c

@@ -4808,7 +4808,7 @@ static void decode_inst_operands(rv_decode *dec, rv_isa isa)
         break;
     case rv_codec_vsetivli:
         dec->rd = operand_rd(inst);
-        dec->imm = operand_vimm(inst);
+        dec->imm = extract32(inst, 15, 5);
         dec->vzimm = operand_vzimm10(inst);
         break;
     case rv_codec_zcb_lb:

disas/riscv.h

@@ -290,7 +290,7 @@ enum {
 #define rv_fmt_fd_vs2                 "O\t3,F"
 #define rv_fmt_vd_vm                  "O\tDm"
 #define rv_fmt_vsetvli                "O\t0,1,v"
-#define rv_fmt_vsetivli               "O\t0,u,v"
+#define rv_fmt_vsetivli               "O\t0,i,v"
 #define rv_fmt_rs1_rs2_zce_ldst       "O\t2,i(1)"
 #define rv_fmt_push_rlist             "O\tx,-i"
 #define rv_fmt_pop_rlist              "O\tx,i"