Add nios2 disassembler support. This patch is composed from binutils files
from commit "Opcodes and assembler support for Nios II R2". The files from
binutils used in this patch are:
include/opcode/nios2.h
include/opcode/nios2r1.h
include/opcode/nios2r2.h
opcodes/nios2-opc.c
opcodes/nios2-dis.c
Checkpatch says total: 114 errors, 0 warnings, 3609 lines checked , which
is caused by a different coding style in those files. These warnings and
errors are not addressed To let these files be easily synchronized between
binutils and qemu.