rtc: isl12022: Drop unneeded OF guards and of_match_ptr()

Drop unneeded OF guards and of_match_ptr(). This allows use of
the driver with other types of firmware such as ACPI PRP0001 based
probing.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://lore.kernel.org/r/20230110140806.87432-4-andriy.shevchenko@linux.intel.com


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