ALSA: hda/hdmi - Fix duplicate unref of pci_dev

Nicholas Johnson reports a null pointer deref as well as a refcount
underflow upon hot-removal of a Thunderbolt-attached AMD eGPU.
He's bisected the issue down to commit 586bc4aa ("ALSA: hda/hdmi -
fix vgaswitcheroo detection for AMD").

The commit iterates over PCI devices using pci_get_class() and
unreferences each device found, even though pci_get_class()
subsequently unreferences the device as well.  Fix it.

Fixes: 586bc4aa ("ALSA: hda/hdmi - fix vgaswitcheroo detection for AMD")
Link: https://lore.kernel.org/r/PSXP216MB0438BFEAA0617283A834E11580580@PSXP216MB0438.KORP216.PROD.OUTLOOK.COM/Reported-and-tested-by: NNicholas Johnson <nicholas.johnson-opensource@outlook.com.au>
Signed-off-by: NLukas Wunner <lukas@wunner.de>
Reviewed-by: NAlex Deucher <alexander.deucher@amd.com>
Cc: Mika Westerberg <mika.westerberg@linux.intel.com>
Cc: Alexander Deucher <alexander.deucher@amd.com>
Cc: Bjorn Helgaas <helgaas@kernel.org>
Link: https://lore.kernel.org/r/77aa6c01aefe1ebc4004e87b0bc714f2759f15c4.1575985006.git.lukas@wunner.deSigned-off-by: NTakashi Iwai <tiwai@suse.de>

sound/pci/hda/hda_intel.c

@@ -1419,7 +1419,6 @@ static bool atpx_present(void)
 				return true;
 			}
 		}
-		pci_dev_put(pdev);
 	}
 	return false;
 }