mount: Fix /run mount.

It turns out that I had messed this up. Issue #173 was addressed anyway
by the followup fix to unpackfs to only exclude the directories that are
actually mounted (which does work), but with this fix, /run is now
handled as intended.

PS: Should the mount job not check the return value of
libcalamares.utils.mount instead of failing silently?

src/modules/mount/mount.conf

@@ -10,8 +10,8 @@ extraMounts:
       mountPoint: /dev
       options: bind
     - device: tmpfs
+      fs: tmpfs
       mountPoint: /run
-      options: tmpfs
 
 extraMountsEfi:
     - device: /sys/firmware/efi