HID: fix hiddev's use of usb_find_interface

My macbook infrared remote control was broken by commit
bd25f4dd6972755579d0ea50d1a5ace2e9b00d1a ("HID: hiddev: use
usb_find_interface, get rid of BKL").

This device appears in dmesg as:
apple 0003:05AC:8242.0001: hiddev0,hidraw0: USB HID v1.11 Device
[Apple Computer, Inc. IR Receiver] on usb-0000:00:1d.2-1/input0

It stopped working as lircd was getting ENODEV when opening /dev/usb/hiddev0.

AFAICS hiddev_driver is a dummy driver so usb_find_interface(&hiddev_driver)
does not find anything.

The device is associated with the usbhid driver, so let's do
usb_find_interface(&hid_driver) instead.

$ ls -l /sys/devices/pci0000:00/0000:00:1d.2/usb7/7-1/7-1:1.0/usb/hiddev0/device/driver
lrwxrwxrwx 1 root root 0 2010-09-12 16:28 /sys/devices/pci0000:00/0000:00:1d.2/usb7/7-1/7-1:1.0/usb/hiddev0/device/driver -> ../../../../../../bus/usb/drivers/usbhid

Signed-off-by: Guillaume Chazarain <guichaz@gmail.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>

drivers/hid/usbhid/hid-core.c

@@ -1446,6 +1446,11 @@ static const struct hid_device_id hid_usb_table[] = {
 	{ }
 };
 
+struct usb_interface *usbhid_find_interface(int minor)
+{
+	return usb_find_interface(&hid_driver, minor);
+}
+
 static struct hid_driver hid_usb_driver = {
 	.name = "generic-usb",
 	.id_table = hid_usb_table,

drivers/hid/usbhid/hiddev.c

@@ -270,7 +270,7 @@ static int hiddev_open(struct inode *inode, struct file *file)
 	struct hiddev *hiddev;
 	int res;
 
-	intf = usb_find_interface(&hiddev_driver, iminor(inode));
+	intf = usbhid_find_interface(iminor(inode));
 	if (!intf)
 		return -ENODEV;
 	hid = usb_get_intfdata(intf);

drivers/hid/usbhid/usbhid.h

@@ -42,6 +42,7 @@ void usbhid_submit_report
 (struct hid_device *hid, struct hid_report *report, unsigned char dir);
 int usbhid_get_power(struct hid_device *hid);
 void usbhid_put_power(struct hid_device *hid);
+struct usb_interface *usbhid_find_interface(int minor);
 
 /* iofl flags */
 #define HID_CTRL_RUNNING	1