gpio: uapi: kernel-doc formatting improvements

Add kernel-doc formatting to all references to structs, enums, fields
and constants, and move deprecation warnings into the Note section of
the deprecated struct.

Replace 'OR:ed' with 'added', as the former looks odd.

Signed-off-by: Kent Gibson <warthog618@gmail.com>
Reviewed-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Link: https://lore.kernel.org/r/20201005070329.21055-4-warthog618@gmail.com
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>