nios2: Add Altera 10M50 GHRD emulation

nios2: Add Altera 10M50 GHRD emulation

Add the Altera 10M50 Nios2 GHRD model. This allows emulating the
10M50 development kit with the Nios2 GHRD loaded in the FPGA. It
is possible to boot Linux kernel and run userspace, thus far only
from initrd as storage support is not yet implemented.

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>
Reviewed-by: Alexander Graf <agraf@suse.de>
Message-Id: <20170118220146.489-7-marex@denx.de>
Signed-off-by: Richard Henderson <rth@twiddle.net>