rtc: rtc7301: Rewrite bindings in schema

rtc: rtc7301: Rewrite bindings in schema

This rewrites the Epson RTC7301 bindings to use YAML schema,
and adds a property for "reg-io-width" as used in several
other bindings to account for different register strides.

The USRobotics USR8200 uses the byte IO width.

Reviewed-by: Rob Herring <robh@kernel.org>
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-v3-1-ade586b62794@linaro.org
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>