HID: ntrig: explain firmware quirk

Commit 6549981bc54777c ("HID: fix N-trig touch panel with recent firmware")
adds a quirk that is needed for devices with more recent firmware so that
they become operational.

As it's not directly obvious from the code why is it needed, a comment
is worthwile.

Signed-off-by: Jiri Kosina <jkosina@suse.cz>
diff --git a/drivers/hid/hid-ntrig.c b/drivers/hid/hid-ntrig.c
index 513db0a..a418f9e 100644
--- a/drivers/hid/hid-ntrig.c
+++ b/drivers/hid/hid-ntrig.c
@@ -352,7 +352,8 @@
 		}
 	}
 
-	report = hdev->report_enum[HID_FEATURE_REPORT].report_id_hash[0x0a]; 
+	/* This is needed for devices with more recent firmware versions */
+	report = hdev->report_enum[HID_FEATURE_REPORT].report_id_hash[0x0a];
 	if (report)
 		usbhid_submit_report(hdev, report, USB_DIR_OUT);