ds2760_battery: cleanups in ds2760_battery_probe()

Removed struct ds2760_platform_data which wasn't defined anywhere.
Indentation cleanups.

Signed-off-by: Daniel Mack <daniel@caiaq.de>
Cc: Szabolcs Gyurko <szabolcs.gyurko@tlt.hu>
Acked-by: Matt Reimer <mreimer@vpop.net>
Signed-off-by: Anton Vorontsov <cbouatmailru@gmail.com>