accessibility: speakup: unregister tty ldisc on later init failures

commit a76acba upstream.

The ldisc registration is intentionally non-fatal, since some synth
drivers do not use tty/ldisc.  However, once speakup_init() continues
past the registration point and later fails, the init unwind path should
mirror speakup_exit() and call spk_ttyio_unregister_ldisc().

Add the missing unregister call to the error path after synth_release(),
matching the normal module exit cleanup order.

Signed-off-by: Haoxiang Li <lihaoxiang@isrc.iscas.ac.cn>
Signed-off-by: Samuel Thibault <samuel.thibault@ens-lyon.org>
Fixes: e23a9b4 ("staging: speakup: safely register and unregister ldisc")
Cc: stable@vger.kernel.org
Link: https://patch.msgid.link/20260531230804.254962-16-samuel.thibault@ens-lyon.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Author: Haoxiang Li

drivers/accessibility/speakup/main.c

@@ -2430,6 +2430,7 @@ static int __init speakup_init(void)
 	mutex_lock(&spk_mutex);
 	synth_release();
 	mutex_unlock(&spk_mutex);
+	spk_ttyio_unregister_ldisc();
 	speakup_kobj_exit();
 
 error_kobjects: