gpio: pca953x: use the correct range when do regmap sync

regmap will sync a range of registers, here use the correct range
to make sure the sync do not touch other unexpected registers.

Find on pca9557pw on imx8qxp/dxl evk board, this device support
8 pin, so only need one register(8 bits) to cover all the 8 pins's
property setting. But when sync the output, we find it actually
update two registers, output register and the following register.

Fixes: b7657430 ("gpio: pca953x: Restore registers after suspend/resume cycle")
Fixes: ec82d1eb ("gpio: pca953x: Zap ad-hoc reg_output cache")
Fixes: 0f25fda8

 ("gpio: pca953x: Zap ad-hoc reg_direction cache")
Signed-off-by: Haibo Chen <haibo.chen@nxp.com>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Signed-off-by: Bartosz Golaszewski <brgl@bgdev.pl>