dt-bindings: pinctrl: Allow values for drive-push-pull and drive-open-drain

A few platforms, at91 and tegra, use drive-push-pull and
drive-open-drain with a 0 or 1 value. There's not really a need for values
as '1' should be equivalent to no value (it wasn't treated that way) and
drive-push-pull disabled is equivalent to drive-open-drain. So dropping the
value can't be done without breaking existing OSs. As we don't want new
cases, mark the case with values as deprecated.

Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Thierry Reding <thierry.reding@gmail.com>
Cc: Jonathan Hunter <jonathanh@nvidia.com>
Cc: Nicolas Ferre <nicolas.ferre@microchip.com>
Cc: Claudiu Beznea <claudiu.beznea@microchip.com>
Signed-off-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20220429194610.2741437-1-robh@kernel.org