mtd: physmap_of: really fix the physmap add-ons

The current way of building the of_physmap add-ons result in just
the add-on being in the object code, and not the actual core
implementation and regress the Gemini and Versatile.

Bake the physmap_of.o object by baking physmap_of_core.o and
adding the Versatile and/or Gemini add-ons to the final object.
Rename the source file physmap_of_core.c to get the desired
build components.

Suggested-by: Boris Brezillon <[e-mail]>
Fixes: 4f04f68e1598 ("mtd: physmap_of: fixup gemini/versatile dependencies")
Signed-off-by: Linus Walleij <[e-mail]>
Acked-by: Boris Brezillon <[e-mail]>
Signed-off-by: Brian Norris <[e-mail]>

drivers/mtd/maps/Makefile

···
 obj-$(CONFIG_MTD_TSUNAMI)	+= tsunami_flash.o
 obj-$(CONFIG_MTD_PXA2XX)	+= pxa2xx-flash.o
 obj-$(CONFIG_MTD_PHYSMAP)	+= physmap.o
-ifdef CONFIG_MTD_PHYSMAP_OF_VERSATILE
-physmap_of-objs += physmap_of_versatile.o
-endif
-ifdef CONFIG_MTD_PHYSMAP_OF_GEMINI
-physmap_of-objs += physmap_of_gemini.o
-endif
+physmap_of-objs-y		+= physmap_of_core.o
+physmap_of-objs-$(CONFIG_MTD_PHYSMAP_OF_VERSATILE) += physmap_of_versatile.o
+physmap_of-objs-$(CONFIG_MTD_PHYSMAP_OF_GEMINI) += physmap_of_gemini.o
+physmap_of-objs			:= $(physmap_of-objs-y)
 obj-$(CONFIG_MTD_PHYSMAP_OF)	+= physmap_of.o
 obj-$(CONFIG_MTD_PISMO)		+= pismo.o
 obj-$(CONFIG_MTD_PMC_MSP_EVM)   += pmcmsp-flash.o