power/reset: Add a new driver implementing 'power off by restarting'

Some devices, Buffalo Linkstation LS-XHL and LS-CHLv2 for example,
power-off by restarting to letting u-boot hold the SoC until the user
presses a key. Add a generic driver to implement this. It binds a function
to pm_power_off, which calls arm_pm_restart.

Signed-off-by: Andrew Lunn <andrew@lunn.ch>
Tested-by: Michael Walle <michael@walle.cc>
Signed-off-by: Anton Vorontsov <anton@enomsg.org>
diff --git a/drivers/power/reset/Kconfig b/drivers/power/reset/Kconfig
index 6453aac..1ae65b8 100644
--- a/drivers/power/reset/Kconfig
+++ b/drivers/power/reset/Kconfig
@@ -22,3 +22,11 @@
 	  commands to the microcontroller which controls the main power.
 
 	  Say Y if you have a QNAP NAS.
+
+config POWER_RESET_RESTART
+	bool "Restart power-off driver"
+	depends on ARM
+	help
+	  Some boards don't actually have the ability to power off.
+	  Instead they restart, and u-boot holds the SoC until the
+	  user presses a key. u-boot then boots into Linux.