power: bq2415x_charger: Delete unnecessary checks before the function call "of_node_put"

The of_node_put() function tests whether its argument is NULL and then
returns immediately. Thus the test around the calls is not needed.

This issue was detected by using the Coccinelle software.

Signed-off-by: Markus Elfring <elfring@users.sourceforge.net>
Acked-by: Pali Rohár <pali.rohar@gmail.com>
Signed-off-by: Sebastian Reichel <sre@kernel.org>