drm/amd: Fix unbind/rebind for VCN 4.0.5

drm/amd: Fix unbind/rebind for VCN 4.0.5

commit 93a01629c8bfd30906c76921ec986802d76920c6 upstream.

Unbinding amdgpu has no problems, but binding it again leads to an
error of sysfs file already existing.  This is because it wasn't
actually cleaned up on unbind.  Add the missing cleanup step.

Fixes: 547aad32edac ("drm/amdgpu: add VCN4 ip block support")
Signed-off-by: Mario Limonciello (AMD) <superm1@kernel.org>
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
(cherry picked from commit d717e62e9b6ccff0e3cec78a58dfbd00858448b3)
Cc: stable@vger.kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>