rtc: sun6i: Use of_property_present() for testing DT property presence

It is preferred to use typed property access functions (i.e.
of_property_read_<type> functions) rather than low-level
of_get_property/of_find_property functions for reading properties. As
part of this, convert of_get_property/of_find_property calls to the
recently added of_property_present() helper when we just want to test
for presence of a property and nothing more.

Signed-off-by: Rob Herring <robh@kernel.org>
Reviewed-by: Jernej Skrabec <jernej.skrabec@gmail.com>
Reviewed-by: Andre Przywara <andre.przywara@arm.com>
Link: https://lore.kernel.org/r/20230310144736.1547041-1-robh@kernel.org


Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>