drm/amdgpu: Increase IH soft ring size for GFX v9.4.3 dGPU

On GFX v9.4.3 dGPU, applications have random timeout failure when XNACK
on, dmesg log has "amdgpu: IH soft ring buffer overflow 0x900, 0x900",
because dGPU mode has 272 cam entries. After increasing IH soft ring
to 512 entries, no more IH soft ring overflow message and application
passed.

Fixes: bf80d34b

 ("drm/amdgpu: Increase soft IH ring size")
Signed-off-by: Philip Yang <Philip.Yang@amd.com>
Reviewed-by: Christian König <christian.koenig@amd.com>
Reviewed-by: Felix Kuehling <Felix.Kuehling@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>