meta-google: ncsid: changing mask dir

"lib" systemd directory conflicts with ncsid, this CL changes the masked
service file to "etc".

Change-Id: I8b1fe615ac3298db0e30c88070a1559cbc172a89
Signed-off-by: Yuxiao Zhang <yuxiaozhang@google.com>
diff --git a/meta-google/recipes-google/ncsi/gbmc-ncsi-config.bb b/meta-google/recipes-google/ncsi/gbmc-ncsi-config.bb
index 9a2179f..29ec5bd 100644
--- a/meta-google/recipes-google/ncsi/gbmc-ncsi-config.bb
+++ b/meta-google/recipes-google/ncsi/gbmc-ncsi-config.bb
@@ -165,8 +165,9 @@
   install -m0755 ${WORKDIR}/gbmc-ncsi-smartnic-wa.sh ${D}${bindir}/
 
   if [ '${GBMC_NCSI_DHCP_IMPERSONATE_HOST}' != 1 ]; then
-    ln -sv /dev/null ${D}${systemd_system_unitdir}/dhcp6@.service
-    ln -sv /dev/null ${D}${systemd_system_unitdir}/dhcp4@.service
+    install -d -m0755  ${D}${sysconfdir}/systemd/system/
+    ln -sv /dev/null ${D}${sysconfdir}/systemd/system/dhcp6@.service
+    ln -sv /dev/null ${D}${sysconfdir}/systemd/system/dhcp4@.service
   fi
 }