riscv: dts: spacemit: Add a PCIe regulator

riscv: dts: spacemit: Add a PCIe regulator

Origin: https://git.kernel.org/linus/73a6c811fa0d07078c9e1eaecea76ce26fb5f10e

Define a 3.3v fixed voltage regulator to be used by PCIe on the
Banana Pi BPI-F3.  On this platform, this regulator is always on.

Signed-off-by: Alex Elder <elder@riscstar.com>
Reviewed-by: Yixun Lan <dlan@gentoo.org>
Tested-by: Yixun Lan <dlan@gentoo.org>
Link: https://lore.kernel.org/r/20251218151235.454997-5-elder@riscstar.com
Signed-off-by: Yixun Lan <dlan@gentoo.org>
Gbp-Pq: Topic features/riscv64
Gbp-Pq: Name riscv-dts-spacemit-Add-a-PCIe-regulator.patch