rtc: xgene: Remove unused struct device in struct xgene_rtc_dev

struct device in struct xgene_rtc_dev is not used, remove it.

Signed-off-by: Nobuhiro Iwamatsu <iwamatsu@nigauri.org>
Link: https://lore.kernel.org/r/20191123090234.32180-1-nobuhiro1.iwamatsu@toshiba.co.jp


Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>