power: supply: rt5033_battery: Move struct rt5033_battery to battery driver

Move struct rt5033_battery from the mfd header into the battery driver because
it's not used by others.

Within struct rt5033_battery, remove the line "struct rt5033_dev *rt5033;"
because it doesn't get used.

In rt5033.h, remove #include <linux/power_supply.h>, it's not necessary
anymore.

In rt5033_battery.c, remove #include <linux/mfd/rt5033.h>, it's not necessary
anymore either. Instead add #include <linux/regmap.h> and

Signed-off-by: Jakob Hauser <jahau@rocketmail.com>
Acked-by: Sebastian Reichel <sebastian.reichel@collabora.com>
Signed-off-by: Lee Jones <lee@kernel.org>
Link: https://lore.kernel.org/r/736e1cbee257853cb3d1da6f05c184e9a053263b.1684182964.git.jahau@rocketmail.com