88pm860x_charger: Drop kfree of devm_kzalloc'd data

The devm_kzalloc function allocates memory that is released automatically,
when a driver detaches. Thus, there is no reason to explicitly call kfree
in probe or remove functions.

Signed-off-by: Jingoo Han <jg1.han@samsung.com>
Signed-off-by: Anton Vorontsov <anton@enomsg.org>