ALSA: lx6464es - remove unused struct member

we cannot set the sampling rate of the device, but can only read it
from the board, so we don't need the member for it.
Signed-off-by: NTim Blechmann <tim@klingt.org>
Signed-off-by: NTakashi Iwai <tiwai@suse.de>

sound/pci/lx6464es/lx6464es.h

@@ -94,7 +94,6 @@ struct lx6464es {
 	uint                    hardware_running[2];
 	u32                     board_sample_rate; /* sample rate read from
 						    * board */
-	u32                     sample_rate;	   /* our sample rate */
 	u16                     pcm_granularity;   /* board blocksize */
 
 	/* dma */