drivers: intc: plic: set edge-triggered register address using compat

Define the edge-trigger register base address based on whether
the PLIC node in the devicetree has an additional compatible
that supports edge-triggered interrupt.

Limited the implementation to Andes NCEPLIC100 only, updated
the devicetree binding of `andes_v5_ae350` accordingly.

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