rename environment.c in env_embedded.c to reflect is functionality

Signed-off-by: Jean-Christophe PLAGNIOL-VILLARD <plagnioj@jcrosoft.com>
diff --git a/cpu/mpc5xx/u-boot.lds b/cpu/mpc5xx/u-boot.lds
index 7434e3f..c83f155 100644
--- a/cpu/mpc5xx/u-boot.lds
+++ b/cpu/mpc5xx/u-boot.lds
@@ -133,7 +133,7 @@
 /*   . = env_start;
 	.ppcenv	:
 	{
-		common/environment.o (.ppcenv)
+		common/env_embedded.o (.ppcenv)
 	}
 */
 }