i2c: tegra: Remove non device-tree support

Tegra has only supported device-tree for platform/board configuration
for quite some time now and so simplify the Tegra I2C driver by dropping
code for non device-tree platforms/boards.

Signed-off-by: Jon Hunter <jonathanh@nvidia.com>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>