Convert CONFIG_BOOTCOUNT_RAM to Kconfig

This converts the following to Kconfig:
  CONFIG_BOOTCOUNT_RAM

Signed-off-by: Alex Kiernan <alex.kiernan@gmail.com>
Reviewed-by: Lukasz Majewski <lukma@denx.de>
diff --git a/drivers/bootcount/Kconfig b/drivers/bootcount/Kconfig
index 40a0755..eabfd13 100644
--- a/drivers/bootcount/Kconfig
+++ b/drivers/bootcount/Kconfig
@@ -40,6 +40,12 @@
 	  So the Userspace Application must set the "upgrade_available"
 	  and "bootcount" variable to 0, if a boot was successfully.
 
+config BOOTCOUNT_RAM
+	bool "Boot counter in RAM"
+	help
+	  Store the bootcount in DRAM protected against against bit errors
+	  due to short power loss or holding a system in RESET.
+
 endchoice
 
 config SYS_BOOTCOUNT_SINGLEWORD