Adds basic platform devices for Loongson 1B, including serial port,
ethernet, USB, RTC and interrupt handler.

The Loongson 1B UART is compatible with NS16550A, the Loongson 1B GMAC is
built around a Synopsys IP Core.

Use normal instead of enhanced descriptors.

Thanks to Giuseppe for updating the normal descriptor in stmmac driver.
Thanks to Zhao Zhang for implementing the RTC driver.
Signed-off-by: NKelvin Cheung <keguang.zhang@gmail.com>
Cc: linux-mips@linux-mips.org
Cc: linux-kernel@vger.kernel.org
Cc: wuzhangjin@gmail.com
Cc: zhzhl555@gmail.com
Cc: Kelvin Cheung <keguang.zhang@gmail.com>
Patchwork: https://patchwork.linux-mips.org/patch/4133/
Patchwork: https://patchwork.linux-mips.org/patch/4134/Signed-off-by: NRalf Baechle <ralf@linux-mips.org>

This patch adds support for the Texas Instruments AR7 System-on-a-Chip.
It supports the TNETD7100, 7200 and 7300 versions of the SoC.
Signed-off-by: NMatteo Croce <matteo@openwrt.org>
Signed-off-by: NFelix Fietkau <nbd@openwrt.org>
Signed-off-by: NEugene Konev <ejka@openwrt.org>
Signed-off-by: NNicolas Thill <nico@openwrt.org>
Signed-off-by: NFlorian Fainelli <florian@openwrt.org>
Signed-off-by: NRalf Baechle <ralf@linux-mips.org>

Signed-off-by: NRalf Baechle <ralf@linux-mips.org>

It was getting a little big, ugly and a primary source for merge conflicts.
Also the old method was a bit too forgiving in that the workaround did
default to off, so now there is an explicit #error forcing platform
maintainers to think if they should enable a workaround for a particular
platform.
Signed-off-by: NRalf Baechle <ralf@linux-mips.org>