ARM: dts: keystone2: add I2C aliases for davinci I2C nodes

Add aliases for I2C nodes required for the DM framework to probe the
davinci-i2c driver.

Signed-off-by: Franklin S Cooper Jr <fcooper@ti.com>
Reviewed-by: Tom Rini <trini@konsulko.com>
Reviewed-by: Heiko Schocher <hs@denx.de>