clk: at91: clk-master: mask mckr against layout->mask

Mask values read/written from/to MCKR against layout->mask as this
mask may be different b/w PMC versions.

Signed-off-by: Claudiu Beznea <claudiu.beznea@microchip.com>
Link: https://lore.kernel.org/r/20211011112719.3951784-10-claudiu.beznea@microchip.com


Acked-by: Nicolas Ferre <nicolas.ferre@microchip.com>
Signed-off-by: Stephen Boyd <sboyd@kernel.org>