Add AHCI support to u-boot

Add AHCI support in u-boot, enable the sata disk controllers which
following the AHCI protocol.

Signed-off-by:Jason Jin<jason.jin@freescale.com>
diff --git a/drivers/Makefile b/drivers/Makefile
index e6176ed..98c4ef9 100644
--- a/drivers/Makefile
+++ b/drivers/Makefile
@@ -44,7 +44,7 @@
 	  serial.o serial_max3100.o \
 	  serial_pl010.o serial_pl011.o serial_xuartlite.o \
 	  sl811_usb.o sm501.o smc91111.o smiLynxEM.o \
-	  status_led.o sym53c8xx.o \
+	  status_led.o sym53c8xx.o ahci.o \
 	  ti_pci1410a.o tigon3.o tsec.o \
 	  usbdcore.o usbdcore_ep0.o usbdcore_omap1510.o usbtty.o \
 	  videomodes.o w83c553f.o \