[udisks2] Only create symlink, if rmdir succeded! Fixes MER#1980
[Master] Fix /rpm/udisks2-symlink-mount-path
Only try to create compatibility symlink, if rmdir'ing OLD_MOUNT_PATH succeded. Otherwise (as in SailfishOS 2.2.x) an symlink named after the last path element of the symlink target is created in OLD_MOUNT_PATH.
Consequently delete such (accidentally crcreated) symlinks first, for this bugfix to work.
Summary: This improvement makes the udisks2-symlink-mount-path script fail-safer and cleans up the havoc it caused, when it failed before.