t7112: remove mention of KNOWN_FAILURE_SUBMODULE_RECURSIVE_NESTED

The known failure mode KNOWN_FAILURE_SUBMODULE_RECURSIVE_NESTED was
removed from lib-submodule-update.sh in 218c883783 (submodule: properly
recurse for read-tree and checkout, 2017-05-02) but at that time this
change was not ported over to topic sb/reset-recurse-submodules, such
that when this topic was merged in 5f074ca7e8 (Merge branch
'sb/reset-recurse-submodules', 2017-05-29), t7112-reset-submodules.sh
kept a mention of this removed failure mode.

Remove it now, as it does not mean anything anymore.

Signed-off-by: Philippe Blain <levraiphilippeblain@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
diff --git a/t/t7112-reset-submodule.sh b/t/t7112-reset-submodule.sh
index a1cb9ff..6734642 100755
--- a/t/t7112-reset-submodule.sh
+++ b/t/t7112-reset-submodule.sh
@@ -5,7 +5,6 @@
 . ./test-lib.sh
 . "$TEST_DIRECTORY"/lib-submodule-update.sh
 
-KNOWN_FAILURE_SUBMODULE_RECURSIVE_NESTED=1
 KNOWN_FAILURE_DIRECTORY_SUBMODULE_CONFLICTS=1
 KNOWN_FAILURE_SUBMODULE_OVERWRITE_IGNORED_UNTRACKED=1