[ALSA] Remove unneeded read/write_size fields in proc text ops

Remove unneeded read/write_size fields in proc text ops.
snd_info_set_text_ops() is fixed, too.

Signed-off-by: Takashi Iwai <tiwai@suse.de>
diff --git a/sound/usb/usbmixer.c b/sound/usb/usbmixer.c
index ce86283..ab921aa 100644
--- a/sound/usb/usbmixer.c
+++ b/sound/usb/usbmixer.c
@@ -1998,7 +1998,7 @@
 		if ((err = snd_audigy2nx_controls_create(mixer)) < 0)
 			goto _error;
 		if (!snd_card_proc_new(chip->card, "audigy2nx", &entry))
-			snd_info_set_text_ops(entry, mixer, 1024,
+			snd_info_set_text_ops(entry, mixer,
 					      snd_audigy2nx_proc_read);
 	}