drm/amdgpu: Fix SDMA HQD destroy error on gfx_v7

[ Upstream commit caaa4c8a6be2a275bd14f2369ee364978ff74704 ]

A wrong register bit was examinated for checking SDMA status so it reports
false failures. This typo only appears on gfx_v7. gfx_v8 checks the correct
bit.

Acked-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Amber Lin <Amber.Lin@amd.com>
Reviewed-by: Felix Kuehling <Felix.Kuehling@amd.com>
Signed-off-by: Felix Kuehling <Felix.Kuehling@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>