drivers: intc: plic: Make function names and types consistent

`get_claim_complete_offset` and `get_threshold_priority_offset` actually
return addresses directly. Rename them to `_addr` for consistency within
the driver. Also change their return type to `mem_addr_t`.

Signed-off-by: Piotr Wojnarowski <pwojnarowski@antmicro.com>
1 file changed