ARM: dts: exynos: Add HDMI and Sil9234 to Trats2 board

Add HDMI and Sil9234 MHL converter to Trats2 board.
Following in SoC devices have been enabled:
- HDMI (HDMI signal encoder),
- Mixer (video buffer scanout device),
- I2C_5 bus (used for HDMI DDC)
- I2C_8 bus (used for HDMI_PHY control).

Based on previous work by:
Tomasz Stanislawski <t.stanislaws@samsung.com>

Signed-off-by: Maciej Purski <m.purski@samsung.com>
Reviewed-by: Andrzej Hajda <a.hajda@samsung.com>
Signed-off-by: Krzysztof Kozlowski <krzk@kernel.org>