clk: meson: gxbb: fix clk_mclk_i958 divider flags

CLK_DIVIDER_ROUND_CLOSEST was incorrectly put in the hw.init flags
while it should have been in the divider flags

Fixes: 3c277c24 ("clk: meson: gxbb: add cts_mclk_i958")
Signed-off-by: Jerome Brunet <jbrunet@baylibre.com>
Signed-off-by: Neil Armstrong <narmstrong@baylibre.com>