ore/exofs: Define new ore_verify_layout

All users of the ore will need to check if current code
supports the given layout. For example RAID5/6 is not
currently supported.

So move all the checks from exofs/super.c to a new
ore_verify_layout() to be used by ore users.

Note that any new layout should be passed through the
ore_verify_layout() because the ore engine will prepare
and verify some internal members of ore_layout, and
assumes it's called.

Signed-off-by: Boaz Harrosh <bharrosh@panasas.com>

diff --cc fs/exofs/inode.c
Simple merge

diff --cc fs/exofs/ore.c
Simple merge

diff --cc fs/exofs/super.c
Simple merge

diff --cc include/scsi/osd_ore.h
Simple merge