meta-ohos-acts: Add mtd, jffs2, block2mtd config fragment

ActsJFFS2Test test suite requires /storage directory to be mounted on jffs2.
To achieve that jffs2 image is mounted on loopdevice using block2mtd module,
therefore mtd, jffs2 and block2mtd modules have to be configured.

Related-To: https://git.ostc-eu.org/OSTC/OHOS/components/staging/xts_acts/-/issues/5


Signed-off-by: Robert Drab <robert.drab@huawei.com>