of: dynamic: Move dead property list check into property add/update functions

The changeset code checks for a property in the deadprops list when
adding/updating a property, but of_add_property() and
of_update_property() do not. As the users of these functions are pretty
simple, they have not hit this scenario or else the property lists
would get corrupted.

With this there are 3 cases of removing a property from either deadprops
or properties lists, so add a helper to find and remove a matching
property.

Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Link: https://lore.kernel.org/r/20230801-dt-changeset-fixes-v3-5-5f0410e007dd@kernel.org
Signed-off-by: Rob Herring <robh@kernel.org>