clk: sunxi-ng: h6-r: Add RTC gate clock

The H6 and H616 feature an (undocumented) bus clock gate for accessing
the RTC registers. This seems to be enabled at reset (or by the BootROM),
so we got away without it so far, but exists regardless.
Since the new RTC clock binding for the H616 requires this "bus" clock
to be specified in the DT, add this to R_CCU clock driver and expose it
on the DT side with a new number.
We do this for both the H6 and H616, but mark it as IGNORE_UNUSED, as we
cannot reference it in any H6 DTs.

Signed-off-by: Andre Przywara <andre.przywara@arm.com>
Reviewed-by: Samuel Holland <samuel@sholland.org>
Signed-off-by: Jernej Skrabec <jernej.skrabec@gmail.com>
Link: https://lore.kernel.org/r/20220428230933.15262-2-andre.przywara@arm.com

clk: sunxi-ng: h6-r: Add R_APB2_RSB clock and reset

While no information about the H6 RSB controller is included in the
datasheet or manual, the vendor BSP and power management blob both
reference the RSB clock parent and register address. These values were
verified by experimentation.

Since this clock/reset are added late, the specifier is added at the end
to maintain the existing DT binding. The code is kept in register order.

Signed-off-by: Samuel Holland <samuel@sholland.org>
Acked-by: Maxime Ripard <mripard@kernel.org>
Signed-off-by: Chen-Yu Tsai <wens@csie.org>

clk: sunxi-ng: add support for H6 PRCM CCU

The H6 has clock/reset controls in PRCM part, like old SoCs such as H3
and A64. However, the PRCM CCU is rearranged; the register arragement
is now similar to the main CCU of H6, and the PRCM now has two APB
buses to control -- one is clocked from AHB clock derivde from AR100
clock, the other is clocked from the same mux with AR100 clock.
Therefore a new driver is written for it.

As there's no official document about the PRCM in H6, all the information
are indirectly collected from BSP and parts of the document, and the
information source is noted as comments in the driver's source code. If
reliable information is provided furtherly, the driver needs to be
rechecked.

Signed-off-by: Icenowy Zheng <icenowy@aosc.io>
Signed-off-by: Maxime Ripard <maxime.ripard@bootlin.com>