kernel: amdgpu/pm: prevent array underflow in vega20_odn_edit_dpm_table()

An array underflow vulnerability was found in the Linux kernel's AMD GPU power management driver. In vega20odneditdpmtable, the inputindex variable is validated to be at most 2 but is not checked for negative values. Since this value is user-controlled via sysfs, a user can provide a negative val...