kernel: make kmod-hwmon-core selected by dependent modules

Currently kmod-hwmon-* will not get into images unless kmod-hwmon-core is added
to DEVICE_PACKAGES as well. By changing the dependencies from "depends on" to
"select", we do not have the issue anymore.

Furthermore, we can remove most occurrences of the package from DEVICE_PACKAGES
and similar variables, as it is now pulled by dependent modules such as:
- kmod-hwmon-gpiofan
- kmod-hwmon-lm63
- kmod-hwmon-lm75
- kmod-hwmon-lm85
- kmod-hwmon-lm90

Signed-off-by: Sungbo Eo <mans0n@gorani.run>
[do not touch ar71xx, adjust line wrapping]
Signed-off-by: Adrian Schmutzler <freifunk@adrianschmutzler.de>