clk: at91: sam9x60: change parent clock from mck_pres to mck_div

ddrck and qspick should have mck_div as parent clocks to be in sync with
linux driver.

Signed-off-by: Mihai Sain <mihai.sain@microchip.com>
Reviewed-by: Claudiu Beznea <claudiu.beznea@microchip.com>