dts: add andestech,nceplic100 binding

Add a new `andestech,nceplic100` binding that inherits from the
`sifive,plic-1.0.0` binding. This is so that the Kconfig
`DT_HAS_ANDESTECH_NCEPLIC100_ENABLED` would be generated during
build.

Signed-off-by: Yong Cong Sin <ycsin@meta.com>
Signed-off-by: Yong Cong Sin <yongcong.sin@gmail.com>