doubletalk: probe failure causes OOPS

The code bothers to probe for the device, but on failing to find it proceeds
to try and release a NULL resource, thereby ruining it's prior good
behaviour

Resolves-Bug: https://bugzilla.kernel.org/show_bug.cgi?id=88581Signed-off-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>

drivers/staging/speakup/speakup_dtlk.c

@@ -361,6 +361,7 @@ static int synth_probe(struct spk_synth *synth)
 	port_val &= 0xfbff;
 	if (port_val != 0x107f) {
 		pr_info("DoubleTalk PC: not found\n");
+		if (synth_lpc)
 			synth_release_region(synth_lpc, SYNTH_IO_EXTENT);
 		return -ENODEV;
 	}