libata: detect Device Attention support

Add a new flag ATA_DFLAG_DA to indicate that device supports "Device
Attention".

Acked-by: Aaron Lu <aaron.lu@amd.com>
Signed-off-by: Lin Ming <ming.m.lin@intel.com>
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>

include/linux/ata.h

@@ -578,6 +578,7 @@ static inline int ata_is_data(u8 prot)
 	  ((u64) (id)[(n) + 0]) )
 
 #define ata_id_cdb_intr(id)	(((id)[ATA_ID_CONFIG] & 0x60) == 0x20)
+#define ata_id_has_da(id)	((id)[77] & (1 << 4))
 
 static inline bool ata_id_has_hipm(const u16 *id)
 {