hw/intc/aspeed: Rename status_addr and addr to status_reg and reg for clarity

hw/intc/aspeed: Rename status_addr and addr to status_reg and reg for clarity

Rename the variables "status_addr" to "status_reg" and "addr" to "reg" because
they are used as register index. This change makes the code more appropriate
and improves readability.

Signed-off-by: Jamin Lin <jamin_lin@aspeedtech.com>
Reviewed-by: Cédric Le Goater <clg@redhat.com>
Link: https://lore.kernel.org/qemu-devel/20250307035945.3698802-3-jamin_lin@aspeedtech.com
Signed-off-by: Cédric Le Goater <clg@redhat.com>