rtc: sun6i: Add support for RTC clocks on R40

rtc: sun6i: Add support for RTC clocks on R40

When support for the R40 in the rtc-sun6i driver was split out for a
separate compatible string, only the RTC half was covered, and not the
clock half. Unfortunately this results in the whole driver not working,
as the RTC half expects the clock half to have been initialized.

Add support for the clock part as well. The clock part is like the H3,
but does not need to export the internal oscillator, nor does it have
a gateable LOSC external output.

This fixes issues with WiFi and Bluetooth not working on the BPI M2U.

Fixes: d6624cc75021 ("rtc: sun6i: Add R40 compatible")
Cc: <stable@vger.kernel.org> # 5.3.x
Signed-off-by: Chen-Yu Tsai <wens@csie.org>
Acked-by: Maxime Ripard <mripard@kernel.org>
Link: https://lore.kernel.org/r/20191205085054.6049-1-wens@kernel.org
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>