libdisasm: fully decode DPI immediate
The immediate value can be rotated.  Instead of dumping the 8-bit immediate
and 4-bit rotate field, we should dump the effective immediate value (both
in decimal and hex) to ease reading the disassembly.  This matches GNU
objdump behavior.

*** 806,820 ****
  
          /*
           * Print the shifter as appropriate
           */
          switch (dpi_inst.dpii_stype) {
!         case ARM_DPI_SHIFTER_IMM32:
!                 len = snprintf(buf, buflen, ", #%d, %d",
!                     dpi_inst.dpii_un.dpii_im.dpisi_imm,
!                     dpi_inst.dpii_un.dpii_im.dpisi_rot);
                  break;
          case ARM_DPI_SHIFTER_SIMM:
                  if (dpi_inst.dpii_un.dpii_si.dpiss_code == DPI_S_NONE) {
                          len = snprintf(buf, buflen, ", %s",
                              arm_reg_names[dpi_inst.dpii_un.dpii_si.dpiss_targ]);
                          break;
--- 806,826 ----
  
          /*
           * Print the shifter as appropriate
           */
          switch (dpi_inst.dpii_stype) {
!         case ARM_DPI_SHIFTER_IMM32: {
!                 uint32_t imm = dpi_inst.dpii_un.dpii_im.dpisi_imm;
!                 int rot = dpi_inst.dpii_un.dpii_im.dpisi_rot * 2;
!                 if (rot != 0)
!                         imm = (imm << (32 - rot)) | (imm >> rot);
!                 if (imm < 10)
!                         len = snprintf(buf, buflen, ", #%d", imm);
!                 else
!                         len = snprintf(buf, buflen, ", #%d  ; %#x", imm, imm);
                  break;
+         }
          case ARM_DPI_SHIFTER_SIMM:
                  if (dpi_inst.dpii_un.dpii_si.dpiss_code == DPI_S_NONE) {
                          len = snprintf(buf, buflen, ", %s",
                              arm_reg_names[dpi_inst.dpii_un.dpii_si.dpiss_targ]);
                          break;