ARM: at91: Move PM init functions to .init_late hook

Move the AT91 PM init functions to .init_late hook to ensure driver
dependencies have probed.

Acked-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Tested-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Signed-off-by: Rob Herring (Arm) <robh@kernel.org>
Link: https://lore.kernel.org/r/20260105-at91-probe-v3-2-594013ff2965@kernel.org
Signed-off-by: Claudiu Beznea <claudiu.beznea@tuxon.dev>