ARM: at91: pm: add quirk for sam9x60's ulp1

On SAM9X60 2 nop operations has to be introduced after setting
WAITMODE bit in CKGR_MOR.

Signed-off-by: Claudiu Beznea <claudiu.beznea@microchip.com>
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Link: https://lore.kernel.org/r/1579522208-19523-9-git-send-email-claudiu.beznea@microchip.com