ppc4xx: Fix APC405 build breakage

This patch fixes APC405 build, by defining CONFIG_PPC4XX_I2C. This is
needed since the move of the PPC4xx I2C driver into the drivers/i2c
directory.

Signed-off-by: Stefan Roese <sr@denx.de>
Cc: Matthias Fuchs <matthias.fuchs@esd.eu>

include/configs/APC405.h

@@ -304,6 +304,7 @@ extern int flash_banks;
  * I2C EEPROM (CAT24WC16) for environment
  */
 #define CONFIG_HARD_I2C			/* I2c with hardware support */
+#define CONFIG_PPC4XX_I2C		/* use PPC4xx driver		*/
 #define CONFIG_SYS_I2C_SPEED		100000	/* I2C speed and slave address */
 #define CONFIG_SYS_I2C_SLAVE		0x7F