clk: mediatek: Add MT2712 clock support

Add MT2712 clock support, include topckgen, apmixedsys,
infracfg, pericfg, mcucfg and subsystem clocks.

Signed-off-by: Weiyi Lu <weiyi.lu@mediatek.com>
[sboyd@codeaurora.org: Static on top_clk_data]
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>