WATCHDOG: Add watchdog driver for OCTEON SOCs

The OCTEON is a MIPS64 based SOC family with an on chip watchdog unit.

The driver is split into two source files one for the C code and one
for assembly.  Assembly is needed to handle the NMI and then print the
machine state before the reboot is triggered.

Signed-off-by: David Daney <ddaney@caviumnetworks.com>
Cc: Wim Van Sebroeck <wim@iguana.be>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Russell King <rmk+kernel@arm.linux.org.uk>
Cc: Tony Lindgren <tony@atomide.com>
Cc: Marc Zyngier <maz@misterjones.org>
Cc: Thierry Reding <thierry.reding@avionic-design.de>
Cc: Sam Ravnborg <sam@ravnborg.org>
To: linux-mips@linux-mips.org
Cc: linux-kernel@vger.kernel.org,
Patchwork: https://patchwork.linux-mips.org/patch/1503/


Signed-off-by: Wim Van Sebroeck <wim@iguana.be>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

 create mode 100644 drivers/watchdog/octeon-wdt-main.c
 create mode 100644 drivers/watchdog/octeon-wdt-nmi.S