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.
Signed-off-by: NMarek Vasut <marex@denx.de>
Cc: Chris Wulff <crwulff@gmail.com>
Cc: Jeff Da Silva <jdasilva@altera.com>
Cc: Ley Foon Tan <lftan@altera.com>
Cc: Sandra Loosemore <sandra@codesourcery.com>
Cc: Yves Vandervennet <yvanderv@altera.com>
Reviewed-by: NAlexander Graf <agraf@suse.de>
Message-Id: <20170118220146.489-2-marex@denx.de>
Signed-off-by: NRichard Henderson <rth@twiddle.net>