rofiles-fuse: Fix permission comparison

We want to allow write if the devinode is in the set,
not the other way around.

https://bugzilla.gnome.org/show_bug.cgi?id=763676

src/rofiles-fuse/main.c

@@ -261,7 +261,7 @@ can_write (const char *path)
       else
 	return -errno;
     }
-  if (devino_set_contains (stbuf.st_dev, stbuf.st_ino))
+  if (!devino_set_contains (stbuf.st_dev, stbuf.st_ino))
     return -EROFS;
   return 0;
 }