drm/amd/pm: fix a potential gpu_metrics_table memory leak

Memory is allocated for gpu_metrics_table in renoir_init_smc_tables(),
but not freed in int smu_v12_0_fini_smc_tables(). Free it!

Fixes: 95868b85 ("drm/amd/powerplay: add Renoir support for gpu metrics export")

Signed-off-by: Lang Yu <lang.yu@amd.com>
Reviewed-by: Lijo Lazar <lijo.lazar@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>