irqchip/bcm-6345-l1: Request memory region

Request memory region in order to display it in /proc/iomem.
Also stop printing the MMIO address since it just displays (ptrval).

Signed-off-by: Álvaro Fernández Rojas <noltari@gmail.com>
Acked-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20230316192833.1603149-1-noltari@gmail.com