gpio: pca953x: use regmap_update_bits() to improve performance

gpio: pca953x: use regmap_update_bits() to improve performance

Using regmap_update_bits() allows to reduce the number of I2C transfers
when updating bits that haven't changed on non-volatile registers.

For example on a PCAL6416, when changing a GPIO direction from input to
output, the number of I2C transfers can be reduced from 4 to just 1 if
the pull resistors configuration hasn't changed and the output value
is the same as before.

Signed-off-by: Hugo Villeneuve <hvilleneuve@dimonoff.com>
Link: https://lore.kernel.org/r/20250714133730.6353-1-hugo@hugovil.com
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>