drm/amdgpu: move gpu_info parsing after common early init

We need to get the silicon revision id before we parse
the firmware in order to load the correct gpu info firmware
for raven2 variants.

Bug: https://gitlab.freedesktop.org/drm/amd/-/issues/1103


Acked-by: Christian König <christian.koenig@amd.com>
Reviewed-by: Evan Quan <evan.quan@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>