Switch back to mksh as the default

Change-Id: I4f39e8d8cc22520cd36f83f8675a716cc1ade1d9
diff --git a/core/config.mk b/core/config.mk
index 9b588cf..7f484aa 100644
--- a/core/config.mk
+++ b/core/config.mk
@@ -106,8 +106,8 @@
 # Default is to prelink modules.
 TARGET_PRELINK_MODULE := true
 
-# Default shell is ash. Other possible value is mksh.
-TARGET_SHELL := ash
+# Default shell is mksh. Other possible value is ash.
+TARGET_SHELL := mksh
 
 # ###############################################################
 # Include sub-configuration files