MRP-1798 mdt: proper error handling in mdt_getattr_name_lock

this is a fix for MRP-975, wrong error handling

also, fix recovery-small 56, so that it checked resend cannot be
handled in parallel with original RPC

Signed-off-by: Vitaly Fertman <Vitaly_Fertman@xyratex.com>
Change-Id: Id96b3018cf53a92d8efa8ec530efce2e73e78024
Reviewed-on: http://es-gerrit.xyus.xyratex.com:8080/1924
Tested-by: Jenkins
Reviewed-by: Alexey Lyashkov <alexey_lyashkov@xyratex.com>
Tested-by: Elena Gryaznova <elena_gryaznova@xyratex.com>
Reviewed-by: Andrew Perepechko <andrew_perepechko@xyratex.com>
Reviewed-by: Vitaly Fertman <vitaly_fertman@xyratex.com>