mount_root: permit to pass mount options for rootfs mount

mount_root: permit to pass mount options for rootfs mount

Introduce an additional arg on calling mount_root start to pass
additional mount options on filesystem mount.

On example is F2FS filesystem mounted with compress_algorithm option
enabled to compress files as they are written to reduce flash wear.

Example usage: (assuming a F2FS filesystem)

mount_root start "compress_algorithm=zstd"

This is currently limited to rootfs mount and is not currently supported
to pass option to rootfs_data mount. (overlay scenario)

Signed-off-by: Christian Marangi <ansuelsmth@gmail.com>