build: s/update-bmc/update_bmc/g

Signed-off-by: Patrick Venture <venture@google.com>
Change-Id: I65f7aa698e41fcee2c603b18fca22d1500850c42
diff --git a/configure.ac b/configure.ac
index 4c5b047..ddf605d 100644
--- a/configure.ac
+++ b/configure.ac
@@ -267,7 +267,7 @@
 )
 AS_IF(
     [test "x$UPDATE_DBUS_SERVICE" == "x"],
-    [UPDATE_DBUS_SERVICE="update-bmc.service"]
+    [UPDATE_DBUS_SERVICE="update_bmc.service"]
 )
 AC_DEFINE_UNQUOTED(
     [UPDATE_DBUS_SERVICE],