clk: mediatek: clk-pll: Add set/clr regs for shared PLL enable control

clk: mediatek: clk-pll: Add set/clr regs for shared PLL enable control

On MT8196, there are set/clr registers to control a shared PLL enable
register. These are intended to prevent different masters from
manipulating the PLLs independently. Add the corresponding en_set_reg
and en_clr_reg fields to the mtk_pll_data structure.

Reviewed-by: Nícolas F. R. A. Prado <nfraprado@collabora.com>
Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Reviewed-by: Chen-Yu Tsai <wenst@chromium.org>
Signed-off-by: Laura Nao <laura.nao@collabora.com>
Signed-off-by: Stephen Boyd <sboyd@kernel.org>