ALSA: wavefront: Replace with __packed attribute

Replace the old __attribute__((packed)) with the new __packed.
Only cleanup, no functional changes.

Link: https://lore.kernel.org/r/20231025132314.5878-10-tiwai@suse.deSigned-off-by: Takashi Iwai <tiwai@suse.de>

include/sound/wavefront.h

@@ -468,7 +468,7 @@ typedef struct wf_alias {
     */
 
     u8 sixteen_bit_padding;
-} __attribute__((packed)) wavefront_alias;
+} __packed wavefront_alias;
 
 typedef struct wf_drum {
     u8 PatchNumber;