rtc: ds1302: Remove unused DRV_NAME

DRV_NAME is unused, remove it.

Signed-off-by: Nobuhiro Iwamatsu <iwamatsu@nigauri.org>
Link: https://lore.kernel.org/r/20191108002354.15016-1-iwamatsu@nigauri.org


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