target-arm: A64: Fix decoding of iss_sf in disas_ld_lit

Fix the decoding of iss_sf in disas_ld_lit.
The SF (Sixty-Four) field in the ISS (Instruction Specific Syndrome)
is a bit that specifies the width of the register that the
instruction loads to.

If cleared it specifies 32 bits.
If set it specifies 64 bits.
Signed-off-by: NEdgar E. Iglesias <edgar.iglesias@xilinx.com>
Message-id: 1475230780-8669-1-git-send-email-edgar.iglesias@gmail.com
[PMM: tweaked phrasing per on-list discussion]
Reviewed-by: NPeter Maydell <peter.maydell@linaro.org>
Signed-off-by: NPeter Maydell <peter.maydell@linaro.org>

target-arm/translate-a64.c

@@ -2025,7 +2025,7 @@ static void disas_ld_lit(DisasContext *s, uint32_t insn)
         do_fp_ld(s, rt, tcg_addr, size);
     } else {
         /* Only unsigned 32bit loads target 32bit registers.  */
-        bool iss_sf = opc == 0 ? 32 : 64;
+        bool iss_sf = opc != 0;
 
         do_gpr_ld(s, tcg_rt, tcg_addr, size, is_signed, false,
                   true, rt, iss_sf, false);