According to the manual the gate clock for MMC3 is at bit 11, and NAND1
is controlled by bit 12.

Fix the gate bit definitions in the clock driver.

Fixes: c6e6c96d ("clk: sunxi-ng: Add A31/A31s clocks")
Signed-off-by: Andre Przywara <andre.przywara@arm.com>
Signed-off-by: Maxime Ripard <maxime.ripard@bootlin.com>