attn: Make attn handler restart less restrictive

Return back to the default service restart limit behavior which is
is a maximum of two failures within 30 seconds before the
attention handler is considered failed. This change is needed as it
seems that the restart count is incremented for every restart not just
the restart after failure. Making the restart more restrictive had the
side effect of the attention handler reaching the restart limit if the
host was restarted  more than two times in 10 minutes even though the
attention handler was not restarted due to failure.

Signed-off-by: Ben Tyner <ben.tyner@ibm.com>
Change-Id: I427d60451dce6b613c6e004a063cea5ad06f8fb5
diff --git a/attn/attn_handler.service.in b/attn/attn_handler.service.in
index b656a64..def8a00 100644
--- a/attn/attn_handler.service.in
+++ b/attn/attn_handler.service.in
@@ -9,7 +9,6 @@
 After=openpower-update-bios-attr-table.service
 Conflicts=obmc-host-stop@0.target
 Conflicts=obmc-host-timeout@0.target
-StartLimitIntervalSec=600
 
 [Service]
 @ENABLE_PHAL_TRUE@Environment="PDBG_DTB=/var/lib/phosphor-software-manager/hostfw/running/DEVTREE"