drm/amd/pm: fix the compile warning

Fix the compile warning below:
drivers/gpu/drm/amd/amdgpu/../pm/legacy-dpm/kv_dpm.c:1641
kv_get_acp_boot_level() warn: always true condition '(table->entries[i]->clk >= 0) => (0-u32max >= 0)'

Reported-by: kernel test robot <lkp@intel.com>
CC: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Evan Quan <evan.quan@amd.com>
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>