[libata] Makefile: Fix build error in sata_highbank

Allow sata_highbank to build even if no other users of libahci.o are built.

Signed-off-by: Mark Langsdorf <mark.langsdorf@calxeda.com>
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>

drivers/ata/Makefile

@@ -9,7 +9,7 @@ obj-$(CONFIG_SATA_FSL)		+= sata_fsl.o
 obj-$(CONFIG_SATA_INIC162X)	+= sata_inic162x.o
 obj-$(CONFIG_SATA_SIL24)	+= sata_sil24.o
 obj-$(CONFIG_SATA_DWC)		+= sata_dwc_460ex.o
-obj-$(CONFIG_SATA_HIGHBANK)	+= sata_highbank.o
+obj-$(CONFIG_SATA_HIGHBANK)	+= sata_highbank.o libahci.o
 
 # SFF w/ custom DMA
 obj-$(CONFIG_PDC_ADMA)		+= pdc_adma.o