drm/amd: Load GFX9 microcode during early_init

If GFX9 microcode is required but not available during early init, the
firmware framebuffer will have already been released and the screen will
freeze.

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