clk: mediatek: clk-mt8195-topckgen: Fix error return code in clk_mt8195_topck_probe()

If devm_clk_hw_register_mux() fails in clk_mt8195_topck_probe(), it should return
error code.

Fixes: deeb2af7

 ("clk: mediatek: clk-mt8195-topckgen: Register mfg_ck_fast_ref as generic mux")
Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>
Link: https://lore.kernel.org/r/20221009025056.35311-1-yangyingliang@huawei.com
Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Signed-off-by: Stephen Boyd <sboyd@kernel.org>