staging/sm7xxfb: return a proper err for smtc_alloc_fb_info failure

as smtc_alloc_fb_info can fail, but we are returning the 0,
how? because the pci_enable_device succeeded, which makes the probe
return 0, and may cause panics or some strange problems at remove
when driver unloaded by modprobe -r.

so return err properly as smtc_alloc_fb_info is doing kzallocs its
good to do -ENOMEM
Signed-off-by: Devendra Naga <devendra.aaru@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/sm7xxfb/sm7xxfb.c

@@ -808,8 +808,10 @@ static int __devinit smtcfb_pci_probe(struct pci_dev *pdev,
 
 	sfb = smtc_alloc_fb_info(pdev, name);
 
-	if (!sfb)
+	if (!sfb) {
+		err = -ENOMEM;
 		goto failed_free;
+	}
 
 	sfb->chip_id = ent->device;
 	sprintf(name, "sm%Xfb", sfb->chip_id);