init.rc: remove commented-out code that set vold.post_fs_data_done

The "vold.post_fs_data_done" system property was only used by FDE, which
is no longer supported, and this code was commented out anyway.

Bug: 208476087
Change-Id: Ib9346d14368c77058a598e5c4f5f2ed72f5a5316