rtc: rx8010: drop unnecessary initialization

The 'err' local variable in rx8010_init_client() doesn't need to be
initialized.

Signed-off-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Link: https://lore.kernel.org/r/20200914154601.32245-9-brgl@bgdev.pl