mmc: meson-gx: cfg init overwrite values

cfg init function overwrite values set in the clk init function
Remove the cfg pokes from the clk init. Actually, trying to use
the CLK_AUTO, like initially tried in clk_init, would break
the card initialization

Reviewed-by: Kevin Hilman <khilman@baylibre.com>
Signed-off-by: Jerome Brunet <jbrunet@baylibre.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>