iio: light: vl6180: Drop unused linux/of.h include

Nothing from linux/of.h is used in this driver.
Reviewed-by: Nuno Sa <nuno.sa@analog.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://lore.kernel.org/r/20240218173323.1023703-2-jic23@kernel.orgSigned-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

drivers/iio/light/vl6180.c

@@ -20,7 +20,6 @@
 #include <linux/i2c.h>
 #include <linux/mutex.h>
 #include <linux/err.h>
-#include <linux/of.h>
 #include <linux/delay.h>
 #include <linux/util_macros.h>