Convert CONFIG_SYS_BOOTCOUNT_SINGLEWORD to Kconfig

This converts the following to Kconfig:
   CONFIG_SYS_BOOTCOUNT_SINGLEWORD

Signed-off-by: Lukasz Majewski <lukma@denx.de>
Tested-by: Alex Kiernan <alex.kiernan@gmail.com>
Reviewed-by: Ian Ray <ian.ray@ge.com>
diff --git a/drivers/bootcount/Kconfig b/drivers/bootcount/Kconfig
index cb6be73..d82289f 100644
--- a/drivers/bootcount/Kconfig
+++ b/drivers/bootcount/Kconfig
@@ -17,6 +17,12 @@
 	  Enable checking for exceeding the boot count limit.
 	  More information: http://www.denx.de/wiki/DULG/UBootBootCountLimit
 
+config SYS_BOOTCOUNT_SINGLEWORD
+	bool "Use single word to pack boot count and magic value"
+	help
+	  This option enables packing boot count magic value and boot count
+	  into single word (32 bits).
+
 if BOOTCOUNT
 
 config BOOTCOUNT_EXT