Fix update-initrd(8) not erroring on missing option arguments.

Remove unimplemented --help and --version options.

update-initrd/update-initrd

@@ -37,8 +37,6 @@ for argument do
   --) dashdash=yes ;;
   --sysroot=*) sysroot=$parameter ;;
   --sysroot) previous_option=sysroot ;;
-  --help) show_help ;;
-  --version) show_version ;;
   -*) echo "$0: unrecognized option $argument" >&2
       $option_checking && exit 1 ;;
   *) echo "$0: unexpected operand $argument" >&2
@@ -46,6 +44,11 @@ for argument do
   esac
 done
 
+if test -n "$previous_option"; then
+  echo "$0: option '$argument' requires an argument" >&2
+  exit 1
+fi
+
 sysmerge=false
 exec_prefix="$sysroot"
 if [ -d "$sysroot/sysmerge" ]; then