ata: add new-style AHCI platform driver for DaVinci DA850 AHCI controller

Add the new ahci_da850 host driver.

Platform changes needed to make DaVinci DA850 SATA AHCI support
fully functional are in the separate "ARM: davinci: da850: update
SATA AHCI support" commit.

Please note that this driver doesn't have the superfluous clock
control code as clock is already handled by the generic AHCI
platform library code.

Cc: Sekhar Nori <nsekhar@ti.com>
Cc: Kevin Hilman <khilman@deeprootsystems.com>
Cc: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
diff --git a/drivers/ata/Kconfig b/drivers/ata/Kconfig
index 12767ad..6e3be7d 100644
--- a/drivers/ata/Kconfig
+++ b/drivers/ata/Kconfig
@@ -97,6 +97,15 @@
 
 	  If unsure, say N.
 
+config AHCI_DA850
+	tristate "DaVinci DA850 AHCI SATA support"
+	depends on ARCH_DAVINCI_DA850
+	help
+	  This option enables support for the DaVinci DA850 SoC's
+	  onboard AHCI SATA.
+
+	  If unsure, say N.
+
 config AHCI_ST
 	tristate "ST AHCI SATA support"
 	depends on ARCH_STI