ALSA: line6: Remove unused line6_nop_read()

The function isn't used any longer after rewriting from sysfs to leds
class in toneport.c.
Tested-by: Chris Rorvick <chris@rorvick.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>

sound/usb/line6/driver.c

@@ -412,16 +412,6 @@ int line6_read_serial_number(struct usb_line6 *line6, int *serial_number)
 }
 EXPORT_SYMBOL_GPL(line6_read_serial_number);
 
-/*
-	No operation (i.e., unsupported).
-*/
-ssize_t line6_nop_read(struct device *dev, struct device_attribute *attr,
-		       char *buf)
-{
-	return 0;
-}
-EXPORT_SYMBOL_GPL(line6_nop_read);
-
 /*
 	Card destructor.
 */

sound/usb/line6/driver.h

@@ -162,8 +162,6 @@ struct usb_line6 {
 
 extern char *line6_alloc_sysex_buffer(struct usb_line6 *line6, int code1,
 				      int code2, int size);
-extern ssize_t line6_nop_read(struct device *dev,
-			      struct device_attribute *attr, char *buf);
 extern int line6_read_data(struct usb_line6 *line6, int address, void *data,
 			   size_t datalen);
 extern int line6_read_serial_number(struct usb_line6 *line6,