LU-3513 tests: sanity 54a, 64b: remove useless check

LU-3513 tests: sanity 54a, 64b: remove useless check

Tests sanity 54a, 64b are skipped if started not from lustre/tests
directory because of incorrect check that $SOCKSERVER, $SOCKCLIENT,
oos.sh exist.

Patch removes the check of the files which are part of lustre/tests.
Error messages are added to indicate what went wrong.

Signed-off-by: Elena Gryaznova <elena_gryaznova@xyratex.com>
Xyratex-bug-id: MRP-982
Signed-off-by: James Nunez <james.a.nunez@intel.com>
Change-Id: I629d8085da393fa9c986076a9913296696444ad0
Reviewed-on: http://review.whamcloud.com/6782
Tested-by: Hudson
Tested-by: Maloo <whamcloud.maloo@gmail.com>
Reviewed-by: Jian Yu <jian.yu@intel.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>