drm/amd: Drop unnecessary helper for aldebaran

aldebaran_get_gpu_power() is only called by one place and just calls
aldebaran_get_smu_metrics_data(), so drop the helper.

Signed-off-by: Mario Limonciello <mario.limonciello@amd.com>
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>