rtc: gemini: fix cocci warnings

Use resource_size function on resource object instead of explicit
computation.

No need to set .owner here. The core will do it.
Remove .owner field if calls are used which set it automatically

Signed-off-by: Fengguang Wu <fengguang.wu@intel.com>
Acked-by: Hans Ulli Kroll <ulli.kroll@googlemail.com>
Signed-off-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>