Move usr-local.mount to common code

The usr-local.mount service is intended to be a directory to patch
firmware. It currently resides under the ubi feature because there
the filesystem is mounted read-only, whereas in the static layout
the root filesystem is mounted on a read-write overlay.

But this service file is not tied to a ubi filesystem, for example
the static layout could be changed to not have an overlay over
root, or a emmc chip would not be formatted as ubi, but would
benefit from this patch directory.

The only current user of this mount service file is the virtual
pnor implementation (openpower-pnor-code-mgmt), which a bmc not
formatted as ubi could choose to use. Therefore move the service
to the common code.

Tested:
- Witherspoon: Verified service is still in the image and was started
  successfully by the pnor updater.
- Romulus: Verified the service is in the image, but does not start
  because it doesn't have the virtual pnor feature. But calling
  'systemctl start usr-local.mount' mounts the directory successfully.

Change-Id: I40d405e0a73f011a3c4de17cdddd8caace80587f
Signed-off-by: Adriana Kobylak <anoo@us.ibm.com>
diff --git a/ubi/Makefile.am.include b/ubi/Makefile.am.include
index f5b834e..51ebf57 100644
--- a/ubi/Makefile.am.include
+++ b/ubi/Makefile.am.include
@@ -14,6 +14,5 @@
 	%reldir%/obmc-flash-bmc-updateubootvars@.service \
 	%reldir%/reboot-guard-disable.service \
 	%reldir%/reboot-guard-enable.service \
-	%reldir%/force-reboot.service \
-	%reldir%/usr-local.mount
+	%reldir%/force-reboot.service
 endif