sim: Check the SimObjectVector.has_parent function to use the "any" function.

sim: Check the SimObjectVector.has_parent function to use the "any" function.

The existing code was essentially doing the same thing, but in a more
roundabout and obscure way. One difference between the two versions is that
I believe this will stop as soon as it encounters an element without a
parent, where the original version would call has_parent() on all the
elements regardless.

Change-Id: Ia1fef3083fc88fca11f8ecfca453476e33194695
Reviewed-on: https://gem5-review.googlesource.com/4842
Reviewed-by: Jason Lowe-Power <jason@lowepower.com>
Maintainer: Gabe Black <gabeblack@google.com>