powerpc/corenet_ds: Correct the compilation errors about ENV

When defined CONFIG_ENV_IS_NOWHERE, there will be some
compilation errors:

./common/env_nowhere.o: In function `env_relocate_spec':
./common/env_nowhere.c:38: multiple definition of `env_relocate_spec'
./common/env_flash.o: ./common/env_flash.c:326: first defined here
./common/env_nowhere.o: In function `env_get_char_spec':
./common/env_nowhere.c:42: multiple definition of `env_get_char_spec'
./common/env_flash.o:./common/env_flash.c:78: first defined here
./common/env_nowhere.o: In function `env_init':
./common/env_nowhere.c:51: multiple definition of `env_init'
./common/env_flash.o:./common/env_flash.c:237: first defined here
make[1]: *** [./common/libcommon.o] Error 1
make[1]: Leaving directory `./common'
make: *** [./common/libcommon.o] Error 2

Remove the CONFIG_ENV_IS_IN_FLASH if defined CONFIG_ENV_IS_NOWHERE.

Signed-off-by: Liu Gang <Gang.Liu@freescale.com>

include/configs/corenet_ds.h

@@ -97,6 +97,8 @@
 #define CONFIG_ENV_IS_IN_NAND
 #define CONFIG_ENV_SIZE			CONFIG_SYS_NAND_BLOCK_SIZE
 #define CONFIG_ENV_OFFSET		(5 * CONFIG_SYS_NAND_BLOCK_SIZE)
+#elif defined(CONFIG_ENV_IS_NOWHERE)
+#define CONFIG_ENV_SIZE		0x2000
 #else
 #define CONFIG_ENV_IS_IN_FLASH
 #define CONFIG_ENV_ADDR		(CONFIG_SYS_MONITOR_BASE - CONFIG_ENV_SECT_SIZE)