rtc: isl12022: Join string literals back

For easy grepping on debug purposes join string literals back in
the messages.

While at it, drop __func__ parameter from unique enough dev_dbg()
message as Dynamic Debug can retrieve this at run time.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Acked-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Link: https://lore.kernel.org/r/20230110140806.87432-5-andriy.shevchenko@linux.intel.com


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