arm64: dts: rockchip: enable NPU on ROCK 5B

arm64: dts: rockchip: enable NPU on ROCK 5B

The NPU on the ROCK5B uses the same regulator for both the sram-supply
and the npu's supply. Add this regulator, and enable all the NPU bits.
Also add the regulator as a domain-supply to the pd_npu power domain.

v8:
- Remove notion of top core (Robin Murphy)

Signed-off-by: Nicolas Frattaroli <nicolas.frattaroli@collabora.com>
Tested-by: Heiko Stuebner <heiko@sntech.de>
Signed-off-by: Tomeu Vizoso <tomeu@tomeuvizoso.net>
Link: https://lore.kernel.org/r/20250721-6-10-rocket-v9-10-77ebd484941e@tomeuvizoso.net
Signed-off-by: Heiko Stuebner <heiko@sntech.de>