The kfree() function was called in one case by the
amdgpu_cgs_acpi_eval_object() function during error handling
even if the passed variable "obj" contained a null pointer.

* Adjust jump targets according to the Linux coding style convention.

* Delete unnecessary initialisations for the variables "obj"
  and "params" then.
Reviewed-by: NChristian König <christian.koenig@amd.com>
Signed-off-by: NMarkus Elfring <elfring@users.sourceforge.net>
Signed-off-by: NAlex Deucher <alexander.deucher@amd.com>