Add resource managed API devm_mfd_add_devices() for the mfd_add_devices().

This helps in reducing code in error path as it is not required
to call mfd_remove_devices() explicitly to remove all child-devices.
In some cases, it also helps not to implement .remove() callback
which get called during driver unbind.
Signed-off-by: Laxman Dewangan <ldewangan@nvidia.com>
Signed-off-by: Lee Jones <lee.jones@linaro.org>