drivers: gpio: bt8xx: prefer dev_err()/dev_warn() over of raw printk

For logging in device contexts, dev_*() functions are preferred over
raw printk(), which also print out device name.

Signed-off-by: Enrico Weigelt, metux IT consult <info@metux.net>
Link: https://lore.kernel.org/r/20201203182423.5499-1-info@metux.net


Signed-off-by: Linus Walleij <linus.walleij@linaro.org>