bootcount: add support for bootcounter on EXT filesystem

Add support for bootcounter on an EXT filesystem.
Sync configuration whitelist.

Signed-off-by: Ian Ray <ian.ray@ge.com>
Signed-off-by: Martyn Welch <martyn.welch@collabora.co.uk>
diff --git a/README b/README
index f288176..6336c5c 100644
--- a/README
+++ b/README
@@ -2362,6 +2362,13 @@
 			CONFIG_SYS_BOOTCOUNT_ADDR = i2c addr which is used for
 						    the bootcounter.
 			CONFIG_BOOTCOUNT_ALEN = address len
+		CONFIG_BOOTCOUNT_EXT
+		enable support for the bootcounter in EXT filesystem
+			CONFIG_SYS_BOOTCOUNT_ADDR = RAM address used for read
+                                                    and write.
+			CONFIG_SYS_BOOTCOUNT_EXT_INTERFACE = interface
+			CONFIG_SYS_BOOTCOUNT_EXT_DEVPART = device and part
+			CONFIG_SYS_BOOTCOUNT_EXT_NAME = filename
 
 - Show boot progress:
 		CONFIG_SHOW_BOOT_PROGRESS