drm/amd/amdgpu: fix SDMA IRQ client ID <-> req mapping.

drm/amd/amdgpu: fix SDMA IRQ client ID <-> req mapping.

sdma has 2 instances in SRIOV cpx mode. Odd numbered VFs have
sdma0/sdma1 instances. Even numbered vfs have sdma2/sdma3. For
Even numbered vfs, the sdma2 & sdma3 (irq srouce id
CLIENTID_SDMA2 and CLIENTID_SDMA3) should map to irq seq 0 & 1.

Signed-off-by: Gavin Wan <Gavin.Wan@amd.com>
Reviewed-by: Hawking Zhang <Hawking.Zhang@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>