sim: enable hw_tree_delete in sim_hw_uninstall

sim: enable hw_tree_delete in sim_hw_uninstall

I can't find any history for why the call to hw_tree_delete is commented
out, and the VCS history shows that this goes back to the original import
in 2009.  I did find some vague reference to it from 2000 (pretty close
to the original import of code), but no actual details.

Without this call, every new instance of the sim results in all old
previously allocated resources being leaked.  With some devices, this
isn't just memory, it's things like open file descriptors or mmaps.

So if there are pending issues with this, I'd rather we get the sims
sorted out rather than continuing to leak this stuff.  Especially since
the "let's wait for the sims to fix themselves" hasn't actually happened
in the last 10+ years.

Signed-off-by: Mike Frysinger <vapier@gentoo.org>