add docs for dt of max8925-mfd, max8925-backlight, and
max8925-battery
Signed-off-by: NQing Xu <qingx@marvell.com>
Signed-off-by: NHaojian Zhuang <haojian.zhuang@gmail.com>
Signed-off-by: NSamuel Ortiz <sameo@linux.intel.com>