gpio: pisosr: Use gpiod_set_value_cansleep in pisosr_gpio_refresh()

This driver has .can_sleep flag set.
So the pisosr_gpio_get() can be called from contexts that can sleep.
Thus use the cansleep() variant in pisosr_gpio_refresh().

Signed-off-by: Axel Lin <axel.lin@ingics.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>