sddm: add pam_limits.so to sddm-autologin.pam

My audio tweaks had stopped working and it took me a while to understand why.

Signed-off-by: Andreas Müller <schnitzeltony@googlemail.com>

recipes-misc/recipes-graphics/sddm/files/sddm-autologin.pam

@@ -5,7 +5,11 @@ auth        required    pam_shells.so
 auth        required    pam_nologin.so
 auth        required    pam_permit.so
 -auth       optional    pam_gnome_keyring.so
+
 account     include     common-account
+
 password    include     common-password
+
 session     include     common-session
+session     required    pam_limits.so
 -session    optional    pam_gnome_keyring.so auto_start