rtc: brcmstb-waketimer: rename irq to wake_irq

rtc: brcmstb-waketimer: rename irq to wake_irq

In preparation for adding a second interrupt to service RTC
interrupts, the existing interrupt is renamed from the generic
'irq' to 'wake_irq' to more clearly convey its role.

It is also converted to an unsigned int.

Finally, the driver message that outputs the IRQ number when
registered is removed since devm_rtc_register_device() already
provides a report of registration and the interrupts can be
found in /proc/interrupts.

Signed-off-by: Doug Berger <opendmb@gmail.com>
Acked-by: Florian Fainelli <f.fainelli@gmail.com>
Link: https://lore.kernel.org/r/20230120190147.718976-5-opendmb@gmail.com
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>