ea20: Convert to generic board

Boards need to select CONFIG_SYS_GENERIC_BOARD in order to
prevent removal from the project.

Signed-off-by: Stefano Babic <sbabic@denx.de>
diff --git a/include/configs/ea20.h b/include/configs/ea20.h
index 9a70aae..2d1f1b3 100644
--- a/include/configs/ea20.h
+++ b/include/configs/ea20.h
@@ -24,6 +24,8 @@
 #define CONFIG_VIDEO
 #define CONFIG_PREBOOT
 
+#define CONFIG_SYS_GENERIC_BOARD
+
 /*
  * SoC Configuration
  */