drm/amdgpu: unlock the correct lock in amdgpu_gfx_enable_kcq()

We changed which lock we are supposed to take but this error path
was accidentally over looked so it still drops the old lock.

Fixes: def799c6 ("drm/amdgpu: add multi-xcc support to amdgpu_gfx interfaces (v4)")
Signed-off-by: Dan Carpenter <dan.carpenter@linaro.org>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>