arm: dts: s5pc1xx-goni: add the pmic node for using DM

To use driver-model adds the pmic node for max8998.
This is used as kerel device-tree in Linux.

Signed-off-by: Jaehoon Chung <jh80.chung@samsung.com>
Signed-off-by: Minkyu Kang <mk7.kang@samsung.com>