ALSA: atiixp_modem: Proper endian notations

The DMA address table in atiixp modem driver is in little-endian,
hence we should define it with __le32 properly.

Spotted by sparse, a warning like:
  sound/pci/atiixp_modem.c:360:28: warning: incorrect type in assignment (different base types)
Signed-off-by: Takashi Iwai <tiwai@suse.de>

sound/pci/atiixp_modem.c

@@ -183,10 +183,10 @@ struct atiixp_modem;
  */
 
 struct atiixp_dma_desc {
-	u32 addr;	/* DMA buffer address */
+	__le32 addr;	/* DMA buffer address */
 	u16 status;	/* status bits */
 	u16 size;	/* size of the packet in dwords */
-	u32 next;	/* address of the next packet descriptor */
+	__le32 next;	/* address of the next packet descriptor */
 };
 
 /*