Add support for emulating Altera NiosII R1 architecture into qemu.
This patch is based on previous work by Chris Wulff from 2012 and
updated to latest mainline QEMU.

Signed-off-by: Marek 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>
Cc: Alexander Graf <agraf@suse.de>
Message-Id: <20170118220146.489-3-marex@denx.de>
[rth: Remove tlb_flush from nios2_cpu_reset.]
Signed-off-by: Richard Henderson <rth@twiddle.net>