i2c: gpio: support write-only sda/scl w/o pull-up

i2c: gpio: support write-only sda/scl w/o pull-up

There are slave devices that understand I2C but have read-only SDA and
SCL. Examples are FD650 7-segment LED controller and its derivatives.
Typical board designs don't even have a pull-up for both pins.
Handle the new attributes for write-only SDA and missing pull-up on
SDA/SCL.

For either pin the open-drain and has-no-pullup properties are
mutually-exclusive, what is documented in the DT property documentation.
We don't add an extra warning here because the open-drain properties
are marked deprecated anyway.

Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
[wsa: switched to device properties]
Signed-off-by: Wolfram Sang <wsa@kernel.org>