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>
diff --git a/configs/kmcoge5ne_defconfig b/configs/kmcoge5ne_defconfig
index 013277c..6bfcee9 100644
--- a/configs/kmcoge5ne_defconfig
+++ b/configs/kmcoge5ne_defconfig
@@ -159,7 +159,6 @@
 CONFIG_LCRR_EADC_2=y
 CONFIG_LCRR_CLKDIV_4=y
 CONFIG_83XX_PCICLK=0x3ef1480
-CONFIG_KM_DEF_NETDEV="eth1"
 CONFIG_SYS_MONITOR_LEN=786432
 CONFIG_OF_BOARD_SETUP=y
 CONFIG_OF_STDOUT_VIA_ALIAS=y
@@ -197,6 +196,7 @@
 CONFIG_MTDPARTS_DEFAULT="mtdparts=boot:768k(u-boot),128k(env),128k(envred),-(ubi0);app:-(ubi1);"
 CONFIG_CMD_UBI=y
 # CONFIG_CMD_UBIFS is not set
+CONFIG_ENV_SOURCE_FILE="km83xx"
 CONFIG_ENV_OVERWRITE=y
 CONFIG_SYS_REDUNDAND_ENVIRONMENT=y
 CONFIG_ENV_ADDR_REDUND=0xF00E0000