clk: thead: th1520-ap: set all AXI clocks to CLK_IS_CRITICAL

In the Linux kernel, the following vulnerability has been resolved: clk: thead: th1520-ap: set all AXI clocks to CLK_IS_CRITICAL The AXI crossbar of TH1520 has no proper timeout handling, which means gating AXI clocks can easily lead to bus timeout and thus system hang. Set all AXI clock gates to CLK_IS_CRITICAL. All these clock gates are ungated by default on system reset. In addition, convert all current CLK_IGNORE_UNUSED usage to CLK_IS_CRITICAL to prevent unwanted clock gating.