befs: dump inode_size superblock information

befs_dump_super_block() wasn't giving the inode_size information when
dumping all elements of the superblock. Add this element to have complete
information of the superblock.

Signed-off-by: Luis de Bethencourt <luisbg@osg.samsung.com>
Signed-off-by: Salah Triki <salah.triki@gmail.com>