clk: mediatek: Add configurable pcw_chg_reg to mtk_pll_data

In previous MediaTek PLL design, it assumes the pcw change control
is always on the CON1 register.
However, the pcw change bit on MT8183 was moved onto CON0 because
the the PCW length of audio PLLs are extended to 32-bit.
Add configurable pcw_chg_reg to set the pcw change control register
address or using the default control register CON1 if without
setting in pll data.

Signed-off-by: Weiyi Lu <weiyi.lu@mediatek.com>
Reviewed-by: James Liao <jamesjj.liao@mediatek.com>
Reviewed-by: Nicolas Boichat <drinkcat@chromium.org>
Tested-by: Nicolas Boichat <drinkcat@chromium.org>
Signed-off-by: Stephen Boyd <sboyd@kernel.org>