modpost complains once these drivers become modules.

 ERROR: modpost: "mtk_mux_gate_clr_set_upd_ops" [drivers/clk/mediatek/clk-mt6779.ko] undefined!

Let's just export them.

Cc: Hanks Chen <hanks.chen@mediatek.com>
Cc: Wendell Lin <wendell.lin@mediatek.com>
Cc: Lee Jones <lee.jones@linaro.org>
Cc: Miles Chen <miles.chen@mediatek.com>
Fixes: 32b028fb ("clk: mediatek: support COMMON_CLK_MEDIATEK module build")
Link: https://lore.kernel.org/r/20210915015540.1732014-1-sboyd@kernel.orgSigned-off-by: Stephen Boyd <sboyd@kernel.org>