drivers: interrupt_controller: intc_clic: add indirect access clic reg

Add indirect CSR access to access CLIC register to satisfy the current
CLIC spec (Version v0.9, 2024-06-28: Draf).

Add CONFIG_LEGACY_CLIC_MEMORYMAP_ACCESS for legacy CLIC implementation
with memory-mapped CLIC register.

Signed-off-by: Jimmy Zheng <jimmyzhe@andestech.com>