ACPI: Remove redundant clearing of context->ret.pointer from acpi_run_osc()

context->ret.pointer already gets set to NULL at the beginning of
acpi_run_osc() and it only gets assigned a new value in the success
path near the end of acpi_run_osc(), so the clearing of
context->ret.pointer (when status != AE_OK) at the end of
acpi_run_osc() is redundant since it will always already be NULL when
status != AE_OK.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Reviewed-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>