scripts/image: drop /sbin from PATH

All programs needed for image creation are available in toolchain.

Signed-off-by: Matthias Reichl <hias@horus.com>

scripts/image

@@ -23,7 +23,6 @@ setup_toolchain target
 function do_mkimage() {
   # Variables used in mkimage script must be passed
   env \
-    PATH="${PATH}:/sbin" \
     ROOT="${ROOT}" \
     SCRIPTS="${SCRIPTS}" \
     TOOLCHAIN="${TOOLCHAIN}" \