arm64: dts: imx8mp-skov: use I2C5 for DDC

arm64: dts: imx8mp-skov: use I2C5 for DDC

The HDMI DDC pads can be muxed either to an i.MX I2C controller or
to a limited I2C controller within the Designware HDMI bridge.

So far, the pads were muxed to the HDMI bridge, but the i.MX I2C controller
is the better choice:

  - The Designware HDMI I2C controller doesn't support multi-byte
    requests and the Linux driver refuses[1] transfers to/from address
    0x37, but these are required for display/brightness configuration,

  - The driver doesn't support I2C bus recovery, but some HDMI panels used
    with the board can be flaky and require it.

As the i.MX I2C controller and driver don't have either of these
limitations, let's make use of it instead.

[1]: https://lore.kernel.org/all/20190722181945.244395-1-mka@chromium.org/

Signed-off-by: Ahmad Fatoum <a.fatoum@pengutronix.de>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>