media: ov5647: Use gpiod_set_value_cansleep

All calls to the gpio library are in contexts that can sleep,
therefore there is no issue with having those GPIOs controlled
by controllers which require sleeping (eg I2C GPIO expanders).

Switch to using gpiod_set_value_cansleep instead of gpiod_set_value
to avoid triggering the warning in gpiolib should the GPIO
controller need to sleep.

Signed-off-by: Dave Stevenson <dave.stevenson@raspberrypi.org>