MAINTAINERS: Match the sun20i family of Allwinner SoCs

Allwinner sunxi SoCs with a RISC-V CPU use the sun20i designator. Match
that pattern in addition to the designators for 32 and 64-bit ARM SoCs.

Acked-by: Jernej Skrabec <jernej.skrabec@gmail.com>
Reviewed-by: Guo Ren <guoren@kernel.org>
Reviewed-by: Heiko Stuebner <heiko@sntech.de>
Signed-off-by: Samuel Holland <samuel@sholland.org>
Acked-by: Conor Dooley <conor.dooley@microchip.com>
Link: https://lore.kernel.org/r/20230126045738.47903-2-samuel@sholland.org


Signed-off-by: Jernej Skrabec <jernej.skrabec@gmail.com>