tests/util/grub-shell: Allow setting the value of debug regardless of its previous state

This allows an invocation of grub-shell to set the value of debug regardless
of the global default environment variable GRUB_SHELL_DEFAULT_DEBUG.

Signed-off-by: Glenn Washburn <development@efficientek.com>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>

tests/util/grub-shell.in

@@ -248,6 +248,8 @@ for option in "$@"; do
 	trim=0 ;;
     --debug)
         debug=$((debug+1)) ;;
+    --debug=*)
+        debug=$((`echo "$option" | sed -e 's/--debug=//'`)) ;;
     --modules=*)
 	ms=`echo "$option" | sed -e 's/--modules=//' -e 's/,/ /g'`
 	modules="$modules $ms" ;;