[SIM, ARM] Fix build failure

[SIM, ARM] Fix build failure

This patch fixes the build failure by using disassembler to get
disassemble function pointer, and do the disassembly, because
print_insn_little_arm is no longer visible outside opcodes/

binutils-gdb/sim/arm/wrapper.c:98:10: error: implicit declaration of function 'print_insn_little_arm' [-Werror=implicit-function-declaration]
   size = print_insn_little_arm (0, & info);
          ^

sim/arm:

2017-09-21  Yao Qi  <yao.qi@linaro.org>

	* wrapper.c (print_insn): Use disassembler instead of
	print_insn_little_arm.