LU-16349 o2iblnd: Fix key mismatch issue

LU-16349 o2iblnd: Fix key mismatch issue

If a pool memory region (mr) is mapped then unmapped without being
used, its key becomes out of sync with the RDMA subsystem.

At pool mr map time, the present code will create a local
invalidate work request (wr) using the mr's present key and then
change the mr's key.  When the mr is first used after being mapped,
the local invalidate wr will invalidate the original mr key, and
then a fast register wr is used with the modified key.  The fast
register will update the RDMA subsystem's key for the mr.

The error occurs when the mr is never used.  The next time the mr
is mapped, a local invalidate wr will again be created, but this
time it will use the mr's modified key.  The RDMA subsystem never
saw the original local invalidate, so now the RDMA subsystem's
key for the mr and o2iblnd's key for the mr are out of sync.

Fix the issue by tracking if the invalidate has been used.
Repurpose the boolean frd->frd_valid.  Presently, frd_valid is
always false.  Remove the code that used frd_valid to conditionally
split the invalidate from the fast register.  Instead, use frd_valid
to indicate when a new invalidate needs to be generated.  After a
post, evaluate if the invalidate was successfully used in the post.

These changes are only meaningful to the FRWR code path.  The failure
has only been observed when using Omni-Path Architecture.

Signed-off-by: Cyril Bordage <cbordage@whamcloud.com>
Change-Id: I532a11f10ae6a5917a4c054f37747d08eb4d6331
Reviewed-on: https://review.whamcloud.com/c/fs/lustre-release/+/49714
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Serguei Smirnov <ssmirnov@whamcloud.com>
Reviewed-by: Amir Shehata <ashehata@whamcloud.com>
Reviewed-by: Frank Sehr <fsehr@whamcloud.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>