[ALSA] portman2x4 - Fix probe error

Reported by Ingo Molnar,
when booting an allyesconfig bzImage kernel the bootup hangs in the
portman2x4 driver (on a box that does not have this hardware), at:
 Pid: 1, comm:              swapper
 EIP: 0060:[<c02f763c>] CPU: 0
 EIP is at parport_pc_read_status+0x4/0x8
  EFLAGS: 00000202    Not tainted  (2.6.23-rc9 #904)
 EAX: f7e57a7f EBX: 00000010 ECX: c2b808c0 EDX: 00000379
 ESI: f7cb8230 EDI: 00000010 EBP: f7cb8230 DS: 007b ES: 007b FS: 0000
 CR0: 8005003b CR2: fff9c000 CR3: 007ec000 CR4: 00000690
 DR0: 00000000 DR1: 00000000 DR2: 00000000 DR3: 00000000
 DR6: ffff0ff0 DR7: 00000400
  [<c04613de>] portman_flush_input+0xde/0x12c
  [<c0461a24>] snd_portman_probe+0x368/0x484
  [<c02fbb8c>] __device_attach+0x0/0x8
  [<c02fce68>] platform_drv_probe+0xc/0x10
  [<c02fba6c>] driver_probe_device+0x74/0x194
  [<c0587174>] klist_next+0x38/0x70
  [<c02fbb8c>] __device_attach+0x0/0x8
  [<c02faea1>] bus_for_each_drv+0x35/0x68
  [<c02fbc22>] device_attach+0x72/0x78
the reason is due to an inconsistent error return code of 1 or 2, while
snd_portman_probe only realizes negative error codes.
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Jaroslav Kysela <perex@perex.cz>

sound/drivers/portman2x4.c

@@ -668,7 +668,7 @@ static int __devinit snd_portman_probe_port(struct parport *p)
 	parport_release(pardev);
 	parport_unregister_device(pardev);
 
-	return res;
+	return res ? -EIO : 0;
 }
 
 static void __devinit snd_portman_attach(struct parport *p)