power: reset: corrections for simple syscon reboot driver

This patch is to fix some bugs in reboot driver. Which includes auto selection
of the MFD_SYSCON for the driver, use of container to locate restart handler,
correction of the count down failure timer and ordering of the header file.

Signed-off-by: Feng Kan <fkan@apm.com>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
[ sre: return err instead of 0 in syscon_reboot_probe() ]
Signed-off-by: Sebastian Reichel <sre@kernel.org>