drm/amdgpu: make sure to init common IP before gmc

Move common IP init before GMC init so that HDP gets
remapped before GMC init which uses it.

This fixes the Unsupported Request error reported through
AER during driver load. The error happens as a write happens
to the remap offset before real remapping is done.

Link: https://bugzilla.kernel.org/show_bug.cgi?id=216373

The error was unnoticed before and got visible because of the commit
referenced below. This doesn't fix anything in the commit below, rather
fixes the issue in amdgpu exposed by the commit. The reference is only
to associate this commit with below one so that both go together.

Fixes: 8795e182

 ("PCI/portdrv: Don't disable AER reporting in get_port_device_capability()")

Acked-by: Christian König <christian.koenig@amd.com>
Reviewed-by: Lijo Lazar <lijo.lazar@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Cc: stable@vger.kernel.org