of: base: Shift refcount decrement in of_find_last_cache_level()

of: base: Shift refcount decrement in of_find_last_cache_level()

Currently, of_find_next_cache_node() and of_property_read_u32()
are called on objects after their refcount have been decremented.
Re-order the calls to decrement the refcount after the function
calls.

Signed-off-by: Pierre Gondois <pierre.gondois@arm.com>
Link: https://lore.kernel.org/r/20220930144936.2882481-1-pierre.gondois@arm.com
Signed-off-by: Rob Herring <robh@kernel.org>