clk: at91: usb: use proper usbs_mask

Use usbs_mask passed as argument. The usbs_mask is different for
SAM9X60.

Fixes: 2423eeae ("clk: at91: usb: Add sam9x60 support")
Signed-off-by: Claudiu Beznea <claudiu.beznea@microchip.com>
Link: https://lkml.kernel.org/r/1579261009-4573-4-git-send-email-claudiu.beznea@microchip.com


Acked-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Signed-off-by: Stephen Boyd <sboyd@kernel.org>