bootcounter: add DM support for memory based bootcounter

add DM/DTS support for the memory based bootcounter
in drivers/bootcount/bootcount.c.

Let the old implementation in, so boards which have
not yet convert to DM/DTS do not break.

Signed-off-by: Heiko Schocher <hs@denx.de>
Reviewed-by: Simon Glass <sjg@chromium.org>
diff --git a/drivers/bootcount/Makefile b/drivers/bootcount/Makefile
index 73ccfb5..059d40d 100644
--- a/drivers/bootcount/Makefile
+++ b/drivers/bootcount/Makefile
@@ -1,6 +1,7 @@
 # SPDX-License-Identifier: GPL-2.0+
 
 obj-$(CONFIG_BOOTCOUNT_GENERIC)	+= bootcount.o
+obj-$(CONFIG_BOOTCOUNT_MEM)	+= bootcount.o
 obj-$(CONFIG_BOOTCOUNT_AT91)	+= bootcount_at91.o
 obj-$(CONFIG_BOOTCOUNT_AM33XX)	+= bootcount_davinci.o
 obj-$(CONFIG_BOOTCOUNT_RAM)	+= bootcount_ram.o