clk: mediatek: pll: Split definitions into separate header file

When the PLL type clk was implemented in the MediaTek clk driver
library, the data structure definitions and function declaration
were put in the common header file.

Since it is its own type of clk, and not all platform clk drivers
utilize it, having the definitions in the common header results
in wasted cycles during compilation.

Split out the related definitions and declarations into its own
header file, and include that only in the platform clk drivers that
need it.

Signed-off-by: Chen-Yu Tsai <wenst@chromium.org>
Reviewed-by: Miles Chen <miles.chen@mediatek.com>
Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Link: https://lore.kernel.org/r/20220208124034.414635-13-wenst@chromium.org


Reviewed-by: Chun-Jie Chen <chun-jie.chen@mediatek.com>
Signed-off-by: Stephen Boyd <sboyd@kernel.org>