dracut-lib.sh: bugfix for pidof function

It appears there is a simple substitution error in the pidof shell function which causes it to fail to find processes.  In my case, processes started by 95nfs are not terminated in the cleanup hook.  This causes knock-on effects disturbing the root filesystem service dependencies.

Enjoy,
Stig Telfer

modules.d/99base/dracut-lib.sh

@@ -976,7 +976,7 @@ if ! command -v pidof >/dev/null 2>/dev/null; then
         for i in /proc/*/exe; do
             [ -e "$i" ] || return 1
             if [ -n "$_exe" ]; then
-                [ "$i" -ef "$_cmd" ] || continue
+                [ "$i" -ef "$_exe" ] || continue
             else
                 _rl=$(readlink -f "$i");
                 [ "${_rl%/$_cmd}" != "$_rl" ] || continue