Blackfin: tweak embedded LDR env config option

Use the common config option for extracting the environment for embedding
into LDR files and clarify the LDR-specific option.

Signed-off-by: Mike Frysinger <vapier@gentoo.org>
diff --git a/include/configs/bf537-srv1.h b/include/configs/bf537-srv1.h
index 7368629..7e9dd36 100644
--- a/include/configs/bf537-srv1.h
+++ b/include/configs/bf537-srv1.h
@@ -115,7 +115,7 @@
 #define CONFIG_ENV_OFFSET	0x10000
 #define CONFIG_ENV_SIZE		0x10000
 #define CONFIG_ENV_SECT_SIZE	0x10000
-#define ENV_IS_EMBEDDED_CUSTOM
+#define CONFIG_ENV_IS_EMBEDDED_IN_LDR
 
 
 /*