of: dynamic: Fix use after free in of_changeset_add_prop_helper()

If the of_changeset_add_property() function call fails, then this code
frees "new_pp" and then dereference it on the next line.  Return the
error code directly instead.

Fixes: c81f6ce1 ("of: dynamic: Fix memleak when of_pci_add_properties() failed")
Signed-off-by: Dan Carpenter <dan.carpenter@linaro.org>
Link: https://lore.kernel.org/r/aKgljjhnpa4lVpdx@stanley.mountain


Signed-off-by: Rob Herring (Arm) <robh@kernel.org>