ahci: fix unaligned access

gcc 4.7 will generate unaligned accesses to local char arrays, so make
them static to avoid that.

Signed-off-by: Rob Herring <rob.herring@calxeda.com>
Reviewed-by: Tom Rini <trini@ti.com>

drivers/block/ahci.c

@@ -610,7 +610,7 @@ static void dump_ataid(hd_driveid_t *ataid)
  */
 static int ata_scsiop_inquiry(ccb *pccb)
 {
-	u8 hdr[] = {
+	static const u8 hdr[] = {
 		0,
 		0,
 		0x5,		/* claim SPC-3 version compatibility */