drm/amdgpu: unlock on error in gfx_v9_4_3_kiq_resume()

Smatch complains that we need to drop this lock before returning.

    drivers/gpu/drm/amd/amdgpu/gfx_v9_4_3.c:1838 gfx_v9_4_3_kiq_resume()
    warn: inconsistent returns 'ring->mqd_obj->tbo.base.resv'.

Fixes: 86301129 ("drm/amdgpu: split gc v9_4_3 functionality from gc v9_0")
Signed-off-by: Dan Carpenter <dan.carpenter@linaro.org>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>