Update the 83xx tree to use I2C support in drivers/fsl_i2c.c.  Delete
cpu/mpc83xx/i2c.c, include/asm-ppc/i2c.h, and all references to those files.
Added multiple I2C bus support to fsl_i2c.c.

Signed-off-by: Timur Tabi <timur@freescale.com>