rtc: pcf8523: always compile pcf8523_rtc_ioctl

Compiling out pcf8523_rtc_ioctl saves about 5% of the generated machine
code. However, it certainly never happens as the RTC character device
interface is the most useful one and is probably always compiled in.

Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Link: https://lore.kernel.org/r/20211018153651.82069-2-alexandre.belloni@bootlin.com