service: remove obmc-mapper dependencies

Mapper is dbus-activated now and this target is removed.  Remove the
dependency as it performs no function.

Signed-off-by: Patrick Williams <patrick@stwcx.xyz>
Change-Id: I2a61198ae29bcd5b98f9f88c5ecbfce677dc7b82
diff --git a/phosphor-virtual-sensor.service.in b/phosphor-virtual-sensor.service.in
index 46996aa..ad4007c 100644
--- a/phosphor-virtual-sensor.service.in
+++ b/phosphor-virtual-sensor.service.in
@@ -1,7 +1,5 @@
 [Unit]
 Description=Virtual sensors
-Wants=obmc-mapper.target
-After=obmc-mapper.target
 
 [Service]
 Restart=always