configs/olpc_xo1: enable JFFS2 image

The machine has a NAND flash device and firmware capable of loading the
OS from a JFFS2 file system on it. Enable creation of JFFS2 image that
can be written to said flash device.

Signed-off-by: Lubomir Rintel <lkundrak@v3.sk>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>

configs/olpc_xo1_defconfig

@@ -21,4 +21,7 @@ BR2_TARGET_ROOTFS_EXT2_4=y
 BR2_TARGET_ROOTFS_EXT2_LABEL="XO1"
 BR2_TARGET_ROOTFS_EXT2_SIZE="32M"
 BR2_TARGET_ROOTFS_EXT2_MKFS_OPTIONS="-O dir_index,^huge_file,^64bit,^extent"
+BR2_TARGET_ROOTFS_JFFS2=y
+BR2_TARGET_ROOTFS_JFFS2_NANDFLASH_128K=y
+BR2_TARGET_ROOTFS_JFFS2_PAD=y
 BR2_PACKAGE_HOST_GENIMAGE=y