drm/amdgpu: Set PFLIP_SUBMITTED for crtc after address update

Also add some pflip debug prints.

This change allows us to wait on pflip status until the new surface address
is actually submitted to the register.

This reverts ed3020e923240829dcdfd3343f6e91dc02c63775
drm/amdgpu: Move MMIO flip out of spinlocked region
The original change assumed DAL will aquire locks inside DAL
implemetion of page_flip callback which eventaully didn't happen.

This moves the flip before status update which makes sense for the
non-DAL code pathes as well.

Signed-off-by: Andrey Grodzovsky <Andrey.Grodzovsky@amd.com>
Reviewed-by: Christian König <christian.koenig@amd.com>
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>