ALSA: hda/hdmi: Register with vga_switcheroo on Dual GPU Macbooks

Commit 586bc4a ("ALSA: hda/hdmi - fix vgaswitcheroo detection for
AMD") caused only AMD gpu's with PX to have their audio component register
with vga_switcheroo. This meant that Apple Macbooks with apple-gmux as the
gpu switcher no longer had the audio client registering, so when the gpu is
powered off by vga_switcheroo snd_hda_intel is unaware that it should have
suspended the device:

amdgpu: switched off
snd_hda_intel 0000:03:00.1:
    Unable to change power state from D3hot to D0, device inaccessible
snd_hda_intel 0000:03:00.1: CORB reset timeout#2, CORBRP = 65535

To resolve this, we use apple_gmux_detect() and register a
vga_switcheroo audio client when apple-gmux is detected.

Fixes: 586bc4a ("ALSA: hda/hdmi - fix vgaswitcheroo detection for AMD")
Link: https://lore.kernel.org/all/[email protected]/
Signed-off-by: Orlando Chamberlain <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Takashi Iwai <[email protected]>

Author: Redecorating

sound/pci/hda/hda_intel.c

@@ -50,6 +50,7 @@
 #include <sound/intel-dsp-config.h>
 #include <linux/vgaarb.h>
 #include <linux/vga_switcheroo.h>
+#include <linux/apple-gmux.h>
 #include <linux/firmware.h>
 #include <sound/hda_codec.h>
 #include "hda_controller.h"
@@ -1463,7 +1464,7 @@ static struct pci_dev *get_bound_vga(struct pci_dev *pci)
 				 * vgaswitcheroo.
 				 */
 				if (((p->class >> 16) == PCI_BASE_CLASS_DISPLAY) &&
-				    atpx_present())
+				    (atpx_present() || apple_gmux_detect(NULL, NULL)))
 					return p;
 				pci_dev_put(p);
 			}