jffs2: Get dev and block size from bdev structure
jffs2: Get dev and block size from bdev structure

There is no need in ioctl actually. Also, now we can use this FS
on HDD

mike2390/embox,Kakadu/embox,embox/embox,embox/embox,embox/embox,mike2390/embox,embox/embox,mike2390/embox,mike2390/embox,embox/embox,Kakadu/embox,mike2390/embox,Kakadu/embox,mike2390/embox,Kakadu/embox,Kakadu/embox,mike2390/embox,Kakadu/embox,embox/embox,Kakadu/embox