arch: add KBUILD_DEFCONFIG to allow "make defconfig" ...

Currently, "make defconfig" is only supported for sandbox and x86.

I set KBUILD_DEFCONFIG to support "make defconfig" where I was able
to find a suitable one.

nios2 and openrisc have a single generic_defconfig, so it is definitely
good for KBUILD_DEFCONFIG.

For arm, mips, I assume qemu is a preferred choice over a real board.

blackfin has only one defconfig. Since it is inactive (it is gone in
Linux), so no more defconfig will come in.

I am not sure about ppc and riscv, so I did not touch them.

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

openrisc: add initial device tree support ...

Signed-off-by: Antony Pavlov <antonynpavlov@gmail.com>
Cc: Franck Jullien <franck.jullien@gmail.com>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

Add __ashrdi3 and remove link to libgcc ...

In a previous patch, Sascha needed to add __ashrdi3 and then linked
to libgcc. This patch add the ashrdi3 function in the arch/openrisc/lib
directory and remove the libgcc dependency.

Signed-off-by: Franck Jullien <franck.jullien@gmail.com>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

openrisc: link to libgcc ...

To get symbols like __ashrdi3.

Franck started generating these symbols from gcc assembly, which seems
to be the cleaner approach. The simpler approach for now to get additional
symbols is to link in libgcc, which is the same as the kernel does.

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
Cc: Franck Jullien <franck.jullien@gmail.com>

Add OpenRISC arch ...

OpenRISC is the original flagship project of the OpenCores community.
This project aims to develop a series of general purpose open source
RISC CPU architectures.

A team from OpenCores provided the first implementation, the OpenRISC
1200, written in the Verilog hardware description language.

Even though I should have created an mach-or1200 directory, it is not
necessary for now. The OpenRISC 1200 CPU is the only one available and
it will be for some time.

Signed-off-by: Franck Jullien <franck.jullien@gmail.com>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>