generic target_skeleton: add /sys to fstab

target/generic/target_skeleton/etc/fstab

@@ -5,4 +5,4 @@
 proc		/proc	       proc     defaults	  0	 0
 devpts		/dev/pts       devpts   defaults,gid=5,mode=620	  0	 0
 tmpfs           /tmp           tmpfs    defaults          0      0
-
+sysfs		/sys	       sysfs    defaults	  0	 0