drivers: i2c: deprecate usage of i2c_atmel_sam3 driver

Atmel SAM3X series has been recently converted to use ASF and
should now use common SAM family drivers. The i2c_atmel_sam3
I2C driver will be removed in the future.

This commit also changes the default I2C driver for Arduino Due
board from i2c_atmel_sam3 to i2c_sam_twi.

Signed-off-by: Piotr Mienkowski <piotr.mienkowski@gmail.com>