hwmon: (adt7475) Add explicit header include

hwmon: (adt7475) Add explicit header include

Since device_property_read_string() and similar functions defined in
linux/property.h are used in the driver add explicit include for
linux/mod_devicetable.h and linux/property.h rather than having implicit
inclusions.
Removed of_match_ptr() improving non-Device Tree compatibility of the
driver and drop unnecessary __maybe_unused.
Header linux/of.h can't be removed yet since macro is_of_node() is used.

Signed-off-by: Flaviu Nistor <flaviu.nistor@gmail.com>
Link: https://lore.kernel.org/r/20260522052352.12139-1-flaviu.nistor@gmail.com
Signed-off-by: Guenter Roeck <linux@roeck-us.net>