pinctrl: pinconf-generic: Add support for "input-schmitt-microvolt" property

Add "input-schmitt-microvolt" property to generic options used for DT
parsing files. This enables drivers, which use generic pin configurations,
to get the value passed to this property.

Signed-off-by: Inochi Amaoto <inochiama@outlook.com>
Link: https://lore.kernel.org/IA1PR20MB4953806785BA04E075DC4F03BBAC2@IA1PR20MB4953.namprd20.prod.outlook.com


Signed-off-by: Linus Walleij <linus.walleij@linaro.org>