rtc: pcf8563: remove useless indirection

pcf8563_rtc_read_time and pcf8563_set_datetime are only used after casting
dev to an i2c_client. Remove that useless indirection.

Link: https://lore.kernel.org/r/20190829212547.19185-4-alexandre.belloni@bootlin.com


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