mtd: nand: davinci: reuse driver for Keystone arch

The Keystone arch has compatible nand device, so reuse it.
In case with Keystone it depends on TI_AEMIF because AEMIF
driver is responsible to set timings.

See http://www.ti.com/lit/ug/sprugz3a/sprugz3a.pdf

Reviewed-by: Grygorii Strashko <[e-mail]>
Reviewed-by: Taras Kondratiuk <[e-mail]>
Signed-off-by: Ivan Khoronzhuk <[e-mail]>
Signed-off-by: Brian Norris <[e-mail]>

Documentation/devicetree/bindings/mtd/davinci-nand.txt

···
-Device tree bindings for Texas instruments Davinci NAND controller
+Device tree bindings for Texas instruments Davinci/Keystone NAND controller
 
-This file provides information, what the device node for the davinci NAND
-interface contains.
+This file provides information, what the device node for the davinci/keystone
+NAND interface contains.
 
 Documentation:
 Davinci DM646x - http://www.ti.com/lit/ug/sprueq7c/sprueq7c.pdf
+Kestone - http://www.ti.com/lit/ug/sprugz3a/sprugz3a.pdf
 
 Required properties:
 
 - compatible:			"ti,davinci-nand"
+				"ti,keystone-nand"
 
 - reg:				Contains 2 offset/length values:
 				- offset and length for the access window.

drivers/mtd/nand/Kconfig

···
 	  for NAND Flash using FLCTL.
 
 config MTD_NAND_DAVINCI
-        tristate "Support NAND on DaVinci SoC"
-        depends on ARCH_DAVINCI
+        tristate "Support NAND on DaVinci/Keystone SoC"
+        depends on ARCH_DAVINCI || (ARCH_KEYSTONE && TI_AEMIF)
         help
 	  Enable the driver for NAND flash chips on Texas Instruments
-	  DaVinci processors.
+	  DaVinci/Keystone processors.
 
 config MTD_NAND_TXX9NDFMC
 	tristate "NAND Flash support for TXx9 SoC"