cmc_pu2: fix implicit declaration of function 'eth_setenv_enetaddr'

Signed-off-by: Jean-Christophe PLAGNIOL-VILLARD <plagnioj@jcrosoft.com>

board/cmc_pu2/load_sernum_ethaddr.c

@@ -27,6 +27,7 @@
 /* #define DEBUG */
 
 #include <common.h>
+#include <net.h>
 
 #define I2C_CHIP	0x50	/* I2C bus address of onboard EEPROM */
 #define I2C_ALEN	1	/* length of EEPROM addresses in bytes */