clk: samsung: exynos3250: fix width field of mout_mmc0/1

As per Exynos3250 user manual mmc0/1 mux selection has 4 bit wide.

Signed-off-by: Pankaj Dubey <pankaj.dubey@samsung.com>
Reviewed-by: Krzysztof Kozlowski <k.kozlowski@samsung.com>
Signed-off-by: Tomasz Figa <tomasz.figa@gmail.com>