power: supply: max17042_battery: Always fall back to default platform-data

It is possible to have CONFIG_OF enabled on x86 builds, where we have no
firmware provided max17042_platform_data. The CONFIG_OF implementation of
max17042_get_pdata would return NULL in this case, causing the probe to
fail.

Instead always fallback to the default platform-data, as used on x86 sofar,
when there is no firmware provided pdata, independent of CONFIG_OF.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.co.uk>