physmap_of: ensure versatile code is reachable

With the newly added physmap_of_versatile code, we get a build error
when physmap_of is in a module, because of_flash_probe_versatile
is not exported:

ERROR: "of_flash_probe_versatile" [drivers/mtd/maps/physmap_of.ko] undefined!

This adds the export, and changes the Makefile so that the code is
also put into a loadable module rather than built-in when physmap_of
itself is a module.
Signed-off-by: Arnd Bergmann <arnd@arndb.de>

drivers/mtd/maps/Makefile

@@ -18,7 +18,9 @@ obj-$(CONFIG_MTD_TSUNAMI)	+= tsunami_flash.o
 obj-$(CONFIG_MTD_PXA2XX)	+= pxa2xx-flash.o
 obj-$(CONFIG_MTD_PHYSMAP)	+= physmap.o
 obj-$(CONFIG_MTD_PHYSMAP_OF)	+= physmap_of.o
-obj-$(CONFIG_MTD_PHYSMAP_OF_VERSATILE) += physmap_of_versatile.o
+ifdef CONFIG_MTD_PHYSMAP_OF_VERSATILE
+obj-$(CONFIG_MTD_PHYSMAP_OF)	+= physmap_of_versatile.o
+endif
 obj-$(CONFIG_MTD_PISMO)		+= pismo.o
 obj-$(CONFIG_MTD_PMC_MSP_EVM)   += pmcmsp-flash.o
 obj-$(CONFIG_MTD_PCMCIA)	+= pcmciamtd.o

drivers/mtd/maps/physmap_of_versatile.c

@@ -19,6 +19,7 @@
  * Foundation, Inc., 59 Temple Place, Suite 330, Boston,
  * MA 02111-1307 USA
  */
+#include <linux/export.h>
 #include <linux/io.h>
 #include <linux/of.h>
 #include <linux/of_address.h>
@@ -251,3 +252,4 @@ int of_flash_probe_versatile(struct platform_device *pdev,
 
 	return 0;
 }
+EXPORT_SYMBOL_GPL(of_flash_probe_versatile);