hid: egalax: Report zero as minimum pressure

The firmware reports a logical minimum of one, but in order for
userspace applications to correctly map all reported values to
non-zero pressure, the driver needs to report a logical minimum of
zero.  Fixed with this patch.
Tested-by: NPhilipp Merkel <mail@philmerk.de>
Cc: Stephane Chatty <chatty@enac.fr>
Signed-off-by: NJiri Kosina <jkosina@suse.cz>
Signed-off-by: NHenrik Rydberg <rydberg@euromail.se>

drivers/hid/hid-egalax.c

@@ -90,6 +90,7 @@ static int egalax_input_mapping(struct hid_device *hdev, struct hid_input *hi,
 			set_abs(input, ABS_MT_TRACKING_ID, field, 0);
 			return 1;
 		case HID_DG_TIPPRESSURE:
+			field->logical_minimum = 0;
 			hid_map_usage(hi, usage, bit, max,
 					EV_ABS, ABS_MT_PRESSURE);
 			set_abs(input, ABS_MT_PRESSURE, field, 0);