drm/amdgpu: Clean up error handling in amdgpu_userq_fence_driver_alloc()

drm/amdgpu: Clean up error handling in amdgpu_userq_fence_driver_alloc()

1) Checkpatch complains if we print an error message for kzalloc()
   failure.  The kzalloc() failure already has it's own error messages
   built in.  Also this allocation is small enough that it is guaranteed
   to succeed.
2) Return directly instead of doing a goto free_fence_drv.  The
   "fence_drv" is already NULL so no cleanup is necessary.

Reviewed-by: Arvind Yadav <arvind.yadav@amd.com>
Signed-off-by: Dan Carpenter <dan.carpenter@linaro.org>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>