staging: lustre: lmv: Error not handled for lmv_find_target

This issue is found by smatch; has been reported as-
Unchecked usage of potential ERR_PTR result in lmv_hsm_req_count
and lmv_hsm_req_build. Added ERR_PTR in both functions and also
return value check added.

Signed-off-by: Ulka Vaze <ulka.vaze@yahoo.in>
Signed-off-by: Aditya Pandit <panditadityashreesh@yahoo.com>
Intel-bug-id: https://jira.hpdd.intel.com/browse/LU-6523
Reviewed-on: http://review.whamcloud.com/14918


Reviewed-by: Dmitry Eremin <dmitry.eremin@intel.com>
Reviewed-by: Andreas Dilger <andreas.dilger@intel.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>
Signed-off-by: James Simmons <jsimmons@infradead.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>