phosphor-dump-monitor- Fix failure for not finding core dump path

phosphot-dump-monitor adds watch on systemd core dump path to
detect any new core files created to initiate a dump. On some
systems systemd core dump package is not pulled, due to this
phosphor-dump monitor service logs error and tries retry for 3 times.

Modified to start phosphor-dump-monitor service only when the
systed core dump path exists.

Tried to add Requires on systedm core dump service but as it is
a template version going with path approach.

Tested:
1) Removed systemd dump folder and restarted dump-monitor service
and ensured that there are no errors logged

Signed-off-by: Marri Devender Rao <devenrao@in.ibm.com>
Change-Id: Ia2bd8adeab70648c183daa71a1f1ca06066aa10a
diff --git a/recipes-phosphor/dump/phosphor-debug-collector/obmc-dump-monitor.service b/recipes-phosphor/dump/phosphor-debug-collector/obmc-dump-monitor.service
index aa3837d..5d1e959 100644
--- a/recipes-phosphor/dump/phosphor-debug-collector/obmc-dump-monitor.service
+++ b/recipes-phosphor/dump/phosphor-debug-collector/obmc-dump-monitor.service
@@ -1,5 +1,6 @@
 [Unit]
 Description=Phosphor Dump core monitor.
+ConditionPathExists=/var/lib/systemd/coredump
 
 [Service]
 ExecStart=/usr/bin/env phosphor-dump-monitor