Remove ConfigFS from Busybox skeleton

It is not included in generic skeleton and very unlikely
that someone will use it on embedded devices.
AFAIK even Fedora does not include it in fstab.

Signed-off-by: Paulius Zaleckas <paulius.zaleckas@gmail.com>
Signed-off-by: Peter Korsgaard <jacmet@sunsite.dk>

target/generic/target_busybox_skeleton/etc/fstab

@@ -5,5 +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
-configfs	/config	       configfs defaults	  0	 0
 sysfs		/sys	       sysfs    defaults	  0	 0