useradd_base: Fix sed command line for passwd-expire

A previous commit tried to add the --follow-symlinks option to
the perform_passwd_expire function in useradd_base.bbclass, however it used
a single -.

This is interpreted as --file=ollow-symlinks which results in...

sed: couldn't open file ollow-symlinks: No such file or directory

and...

ERROR: <image name>: passwd --expire operation did not succeed.

Fix by adding the missing -

(From OE-Core rev: 3c0deafcfcea3f610c7dd9a2d2884a16fbfe0497)

Signed-off-by:  Adam Johnston <adam.johnston@arm.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

meta/classes/useradd_base.bbclass

@@ -160,7 +160,7 @@ perform_passwd_expire () {
 	local username=`echo "$opts" | awk '{ print $NF }'`
 	local user_exists="`grep "^$username:" $rootdir/etc/passwd || true`"
 	if test "x$user_exists" != "x"; then
-		eval flock -x $rootdir${sysconfdir} -c \"$PSEUDO sed -follow-symlinks -i \''s/^\('$username':[^:]*\):[^:]*:/\1:0:/'\' $rootdir/etc/shadow \" || true
+		eval flock -x $rootdir${sysconfdir} -c \"$PSEUDO sed --follow-symlinks -i \''s/^\('$username':[^:]*\):[^:]*:/\1:0:/'\' $rootdir/etc/shadow \" || true
 		local passwd_lastchanged="`grep "^$username:" $rootdir/etc/shadow | cut -d: -f3`"
 		if test "x$passwd_lastchanged" != "x0"; then
 			bbfatal "${PN}: passwd --expire operation did not succeed."