mtd: allow CONFIG_MTD_PHYSMAP_OF also for CONFIG_MTD_RAM

Up to now mtd-ram devices described in device trees were only accessible
if mtd-flash or mtd-rom were also configured at linux configuration
time, because MTD_PHYSMAP_OF was only available if (MTD_CFI ||
MTD_JEDECPROBE || MTD_ROM).  Allow MTD_PHYSMAP_OF selection also
when only MTD_RAM is set.
Signed-off-by: NPhilippe De Muyter <phdm@macqel.be>
Signed-off-by: NBrian Norris <computersforpeace@gmail.com>

drivers/mtd/maps/Kconfig

@@ -66,11 +66,11 @@ config MTD_PHYSMAP_BANKWIDTH
 	  used internally by the CFI drivers.
 
 config MTD_PHYSMAP_OF
-	tristate "Flash device in physical memory map based on OF description"
-	depends on OF && (MTD_CFI || MTD_JEDECPROBE || MTD_ROM)
+	tristate "Memory device in physical memory map based on OF description"
+	depends on OF && (MTD_CFI || MTD_JEDECPROBE || MTD_ROM || MTD_RAM)
 	help
-	  This provides a 'mapping' driver which allows the NOR Flash and
-	  ROM driver code to communicate with chips which are mapped
+	  This provides a 'mapping' driver which allows the NOR Flash, ROM
+	  and RAM driver code to communicate with chips which are mapped
 	  physically into the CPU's memory. The mapping description here is
 	  taken from OF device tree.