km/powerpc: migrate to env.txt file

Use already present common.env file and add a powerpc specific env
so that we can move all the environment defines to text files.

Signed-off-by: Holger Brunck <holger.brunck@hitachienergy.com>

board/keymile/km83xx/km83xx.env

@@ -0,0 +1,21 @@
+#if CONFIG_TARGET_KMCOGE5NE
+#define WCOM_UBI_PARTITION_APP
+hostname=kmcoge5ne
+netdev=eth1
+uimage=ecc_bch_uImage
+#elif CONFIG_TARGET_KMETER1
+hostname=kmeter1
+netdev=eth2
+uimage=uImage
+#else
+hostname=kmeter1
+netdev=eth0
+uimage=uImage
+#endif
+
+#include <environment/pg-wcom/common.env>
+#include <environment/pg-wcom/powerpc.env>
+
+#if CONFIG_TARGET_KMCOGE5NE
+add_default+= eccmode=bch
+#endif