kbuild: fix adjust_autoksyms.sh for modules that need only one symbol

When only one symbol was listed and therefore the line didn't contain
any space to separate multiple symbols, that symbol got ignored.

Reported-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Nicolas Pitre <nico@linaro.org>
Signed-off-by: Michal Marek <mmarek@suse.com>
diff --git a/scripts/adjust_autoksyms.sh b/scripts/adjust_autoksyms.sh
index 5bf538f..8dc1918 100755
--- a/scripts/adjust_autoksyms.sh
+++ b/scripts/adjust_autoksyms.sh
@@ -59,7 +59,7 @@
  */
 
 EOT
-sed -ns -e '3s/ /\n/gp' "$MODVERDIR"/*.mod | sort -u |
+sed -ns -e '3{s/ /\n/g;/^$/!p;}' "$MODVERDIR"/*.mod | sort -u |
 while read sym; do
 	if [ -n "$CONFIG_HAVE_UNDERSCORE_SYMBOL_PREFIX" ]; then
 		sym="${sym#_}"