linux-phytec-ti

rtc: remove .open() and .release()

There are no driver left using .open and .release. There is no good use
case for them as there is nothing the character device interface does that
should not be done in the sysfs interface or in-kernel interface.

Remove those callbacks now to avoid future confusion.

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