fs: btrfs: Add U-Boot fs handlers.

Signed-off-by: Marek Behun <marek.behun@nic.cz>

 create mode 100644 fs/btrfs/Kconfig
 create mode 100644 fs/btrfs/Makefile
 create mode 100644 fs/btrfs/btrfs.c
 create mode 100644 include/btrfs.h
diff --git a/fs/btrfs/Kconfig b/fs/btrfs/Kconfig
new file mode 100644
index 0000000..22909d9
--- /dev/null
+++ b/fs/btrfs/Kconfig
@@ -0,0 +1,9 @@
+config FS_BTRFS
+	bool "Enable BTRFS filesystem support"
+	select CRC32C
+	select LZO
+	select RBTREE
+	help
+	  This provides a single-device read-only BTRFS support. BTRFS is a
+	  next-generation Linux file system based on the copy-on-write
+	  principle.