Add support for Sil680 IDE controller.

o add drivers/sil680.c to support the Sil680 IDE-controller.
o drivers/Makefile: add sil680.o.

Signed-off-by: Gary Jennejohn <garyj@denx.de>
diff --git a/drivers/Makefile b/drivers/Makefile
index 3ee6312..6bf05cc 100755
--- a/drivers/Makefile
+++ b/drivers/Makefile
@@ -43,7 +43,7 @@
 	  sed13806.o sed156x.o \
 	  serial.o serial_max3100.o \
 	  serial_pl010.o serial_pl011.o serial_xuartlite.o \
-	  sl811_usb.o sm501.o smc91111.o smiLynxEM.o \
+	  sil680.o sl811_usb.o sm501.o smc91111.o smiLynxEM.o \
 	  status_led.o sym53c8xx.o systemace.o ahci.o \
 	  ti_pci1410a.o tigon3.o tsec.o \
 	  tsi108_eth.o tsi108_i2c.o tsi108_pci.o \