OPP: add index check to assert to avoid buffer overflow in _read_freq()

In the Linux kernel, the following vulnerability has been resolved: OPP: add index check to assert to avoid buffer overflow in _read_freq() Pass the freq index to the assert function to make sure we do not read a freq out of the opp->rates[] table when called from the indexed variants: dev_pm_opp_find_freq_exact_indexed() or dev_pm_opp_find_freq_ceil/floor_indexed(). Add a secondary parameter to the assert function, unused for assert_single_clk() then add assert_clk_index() which will check for the clock index when called from the _indexed() find functions.