drm/amdgpu: Add interrupt SQ source struct to amdgpu_gfx struct v2.

SQ can generate interrupts on EDC/ECC errors and this struct controls
how the interrupt is handled.  The guts are filled in in the
gf_v<major>_<minor>.c files.

v2:
Rebase.

Signed-off-by: David Panariti <David.Panariti@amd.com>
Reviewed-by: Nicolai Hähnle <nicolai.haehnle@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>