HID: i2c-hid: switch to standard debugging APIs

Instead of implementing a custom form of dynamic debugging we can use
the standard debugging APIs. If the kernel is built with
CONFIG_DYNAMIC_DEBUG this will be more discoverable and featureful.

Also the previous module parameter "debug" is read-only so it can't
actually be enabled.

Signed-off-by: Thomas Weißschuh <linux@weissschuh.net>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>