fs/f2fs: add support for creating a f2fs image

This patch makes possible to create rootfs image using f2fs
filesystem.

Signed-off-by: Grzegorz Blach <grzegorz@blach.pl>
[Thomas:
 - keep only the minimal functionality, as suggested by Yann E. Morin
 - use truncate -s instead of dd to create the initial empty image
   file, as suggested by Yann E. Morin]
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>
3 files changed