The old RTC7301 driver in OpenWrt used byte access, but the
current mainline Linux driver uses 32bit word access.

Make this configurable using device properties using the
standard property "reg-io-width" in e.g. device tree.

This is needed for the USRobotics USR8200 which has the
chip connected using byte accesses.

Debugging and testing by Howard Harte.
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Reviewed-by: Akinobu Mita <akinobu.mita@gmail.com>
Link: https://lore.kernel.org/r/20231010-rtc-7301-regwidth-v3-2-ade586b62794@linaro.orgSigned-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>