poweprc/km82xx: add board specific environment variable

On mgcoge3ne a new environment variable bobcatreset is used.
So this patch adds a possibility to add board specific
environment variables in general and this specific variable
for mgcoge3ne.

Signed-off-by: Holger Brunck <holger.brunck@keymile.com>
Acked-by: Heiko Schocher <hs@denx.de>
cc: Wolfgang Denk <wd@denx.de>
cc: Detlev Zundel <dzu@denx.de>
cc: Valentin Longchamp <valentin.longchamp@keymile.com>
Signed-off-by: Valentin Longchamp <valentin.longchamp@keymile.com>
diff --git a/include/configs/km82xx-common.h b/include/configs/km82xx-common.h
index 894e015..446c1d0 100644
--- a/include/configs/km82xx-common.h
+++ b/include/configs/km82xx-common.h
@@ -80,6 +80,7 @@
  * Default environment settings
  */
 #define	CONFIG_EXTRA_ENV_SETTINGS					\
+	CONFIG_KM_BOARD_EXTRA_ENV					\
 	CONFIG_KM_DEF_ENV						\
 	"EEprom_ivm=pca9544a:70:4 \0"					\
 	"unlock=yes\0"							\