RISC-V: Use static xlen on ADDIW sequence

Because XLEN for the disassembler is computed and stored in the xlen
variable, this commit replaces uses of info->mach with xlen
(when testing for ADDIW / C.ADDIW address sequence).

Not just we used two ways to determine current XLEN, info->mach and xlen,
xlen is going to be more important in the future commits.

opcodes/ChangeLog:

	* riscv-dis.c (print_insn_args): Use xlen variable to determine
	whether XLEN is larger than 32.

Author: a4lg

opcodes/riscv-dis.c

@@ -261,7 +261,7 @@ print_insn_args (const char *oparg, insn_t l, bfd_vma pc, disassemble_info *info
 	    case 'j':
 	      if (((l & MASK_C_ADDI) == MATCH_C_ADDI) && rd != 0)
 		maybe_print_address (pd, rd, EXTRACT_CITYPE_IMM (l), 0);
-	      if (info->mach == bfd_mach_riscv64
+	      if (xlen > 32
 		  && ((l & MASK_C_ADDIW) == MATCH_C_ADDIW) && rd != 0)
 		maybe_print_address (pd, rd, EXTRACT_CITYPE_IMM (l), 1);
 	      print (info->stream, dis_style_immediate, "%d",
@@ -461,7 +461,7 @@ print_insn_args (const char *oparg, insn_t l, bfd_vma pc, disassemble_info *info
 	  if (((l & MASK_ADDI) == MATCH_ADDI && rs1 != 0)
 	      || (l & MASK_JALR) == MATCH_JALR)
 	    maybe_print_address (pd, rs1, EXTRACT_ITYPE_IMM (l), 0);
-	  if (info->mach == bfd_mach_riscv64
+	  if (xlen > 32
 	      && ((l & MASK_ADDIW) == MATCH_ADDIW) && rs1 != 0)
 	    maybe_print_address (pd, rs1, EXTRACT_ITYPE_IMM (l), 1);
 	  print (info->stream, dis_style_immediate, "%d",