clk: sunxi-ng: Fix div/mult settings for osc12M on A64

The mult/div for osc12M was previously backwards (giving a 48M rate
for osc12M). Fix it.

Signed-off-by: Philipp Tomsich <philipp.tomsich@theobroma-systems.com>
Tested-by: Christoph Muellner <christoph.muellner@theobroma-systems.com>
Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>