drm/amdgpu: avoid buffer overflow attach in smu_sys_set_pp_table()

In the Linux kernel, the following vulnerability has been resolved: drm/amdgpu: avoid buffer overflow attach in smu_sys_set_pp_table() It malicious user provides a small pptable through sysfs and then a bigger pptable, it may cause buffer overflow attack in function smu_sys_set_pp_table().