HID: make hid_report_len as a static inline function in hid.h

In several hid drivers it is necessary to calculate the length of an
hid_report. This patch exports the existing static function hid_report_len of
hid-core.c as an inline function in hid.h

Signed-off-by: Mathieu Magnaudet <mathieu.magnaudet@enac.fr>
Reviewed-by: Benjamin Tissoires <benjamin.tissoires@gmail.com>
Reviewed-by: David Herrmann <dh.herrmann@gmail.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
diff --git a/include/linux/hid.h b/include/linux/hid.h
index 78ea9bf..2366fda 100644
--- a/include/linux/hid.h
+++ b/include/linux/hid.h
@@ -1063,6 +1063,17 @@
 		hdev->ll_driver->wait(hdev);
 }
 
+/**
+ * hid_report_len - calculate the report length
+ *
+ * @report: the report we want to know the length
+ */
+static inline int hid_report_len(struct hid_report *report)
+{
+	/* equivalent to DIV_ROUND_UP(report->size, 8) + !!(report->id > 0) */
+	return ((report->size - 1) >> 3) + 1 + (report->id > 0);
+}
+
 int hid_report_raw_event(struct hid_device *hid, int type, u8 *data, int size,
 		int interrupt);