Simplify the PATH for mga3+

--- dropbear-2014.65/options.h.orig	2012-02-23 14:47:06.000000000 +0100
+++ dropbear-2014.65/options.h	2013-06-13 22:30:23.000000000 +0200
@@ -318,7 +318,7 @@
 #define DEFAULT_IDLE_TIMEOUT 0
 
 /* The default path. This will often get replaced by the shell */
-#define DEFAULT_PATH "/usr/bin:/bin"
+#define DEFAULT_PATH "/usr/bin"
 
 /* Some other defines (that mostly should be left alone) are defined
  * in sysoptions.h */