iio: merge hid-sensor-attributes.h into hid-sensor-hub.h

The stuff in hid-sensor-attributes.h is needed by every piece which
uses hid-sensor-hub and merging it into hid-sensor-hub.h makes it accessible
from outside the iio subdirectory.

Signed-off-by: Alexander Holler <holler@ahsoftware.de>
Acked-by: Jiri Kosina <jkosina@suse.cz>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

drivers/iio/accel/hid-sensor-accel-3d.c

@@ -28,7 +28,6 @@
 #include <linux/iio/buffer.h>
 #include <linux/iio/trigger_consumer.h>
 #include <linux/iio/triggered_buffer.h>
-#include "../common/hid-sensors/hid-sensor-attributes.h"
 #include "../common/hid-sensors/hid-sensor-trigger.h"
 
 /*Format: HID-SENSOR-usage_id_in_hex*/