accessiblity: speakup: Add missing misc_deregister in softsynth_probe

softsynth_probe misses a call misc_deregister() in an error path, this
patch fixes that.

Signed-off-by: Zheng Bin <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Greg Kroah-Hartman <[e-mail]>

drivers/accessibility/speakup/speakup_soft.c

···
 	synthu_device.name = "softsynthu";
 	synthu_device.fops = &softsynthu_fops;
 	if (misc_register(&synthu_device)) {
+		misc_deregister(&synth_device);
 		pr_warn("Couldn't initialize miscdevice /dev/softsynthu.\n");
 		return -ENODEV;
 	}