ahci: Cache host controller version

This allows sysfs nodes to read the cached value directly instead of
powering up possibly runtime suspended controller.

Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
diff --git a/drivers/ata/ahci.h b/drivers/ata/ahci.h
index 167ba7e..70b06bc 100644
--- a/drivers/ata/ahci.h
+++ b/drivers/ata/ahci.h
@@ -335,6 +335,7 @@
 	void __iomem *		mmio;		/* bus-independent mem map */
 	u32			cap;		/* cap to use */
 	u32			cap2;		/* cap2 to use */
+	u32			version;	/* cached version */
 	u32			port_map;	/* port map to use */
 	u32			saved_cap;	/* saved initial cap */
 	u32			saved_cap2;	/* saved initial cap2 */