i2c: Move PPC4xx I2C driver into drivers/i2c directory

This patch moves the PPC4xx specific I2C device driver into the I2C
drivers directory. All 4xx config headers are updated to include this
driver.

Signed-off-by: Stefan Roese <sr@denx.de>
diff --git a/include/configs/METROBOX.h b/include/configs/METROBOX.h
index 518173a..e7429dd 100644
--- a/include/configs/METROBOX.h
+++ b/include/configs/METROBOX.h
@@ -194,6 +194,7 @@
  *----------------------------------------------------------------------*/
 #define CONFIG_HARD_I2C	      1		     /* I2C hardware support	*/
 #undef	CONFIG_SOFT_I2C			     /* I2C !bit-banged		*/
+#define CONFIG_PPC4XX_I2C		/* use PPC4xx driver		*/
 #define CONFIG_SYS_I2C_SPEED	      400000	     /* I2C speed 400kHz	*/
 #define CONFIG_SYS_I2C_SLAVE	      0x7F	     /* I2C slave address	*/
 #define CONFIG_SYS_I2C_NOPROBES      {0x69}	     /* Don't probe these addrs */