The R40 has an RTC hardware block, which has additional registers
that are not related to RTC or clock functions, and is otherwise
compatible with the H3's RTC.

Add a device node for it, and fix up any references to the LOSC.
Acked-by: Maxime Ripard <maxime.ripard@bootlin.com>
Tested-by: Corentin Labbe <clabbe.montjoie@gmail.com>
Signed-off-by: Chen-Yu Tsai <wens@csie.org>