reset: Create subdirectory for SpacemiT drivers

reset: Create subdirectory for SpacemiT drivers

Create a dedicated subdirectory for SpacemiT reset drivers to allow
for better organization as support for more SoCs is added.

Move the existing K1 reset driver into this new directory and rename
it to reset-spacemit-k1.c.

Rename the Kconfig symbol to RESET_SPACEMIT_K1 and update its default
from ARCH_SPACEMIT to SPACEMIT_K1_CCU. The reset driver depends on the
clock driver to register reset devices as an auxiliary device, so the
default should reflect this dependency.

Also sort the drivers/reset/Kconfig entries alphabetically.

Reviewed-by: Alex Elder <elder@riscstar.com>
Signed-off-by: Guodong Xu <guodong@riscstar.com>
Reviewed-by: Yixun Lan <dlan@kernel.org>
Link: https://lore.kernel.org/spacemit/20260114092742-GYC7933267@gentoo.org/
Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>