rtc: isl12022: use %ptR

Simplify the code and make the output format consistent with other RTC
drivers by standardizing on using the %ptR printf extension.

Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Link: https://lore.kernel.org/r/20220921114624.3250848-6-linux@rasmusvillemoes.dk


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