fbdev: omap2: connector-dvi: use of_get_i2c_adapter_by_node interface

This change is needed to properly lock I2C bus driver, which serves DDC.

Prior to this change i2c_put_adapter() is misused, which may lead to
an overflow over zero of I2C bus driver user counter.

Signed-off-by: Vladimir Zapolskiy <vladimir_zapolskiy@mentor.com>
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>