ALSA: hda: constify pci_device_id.

pci_device_id are not supposed to change at runtime. All functions
working with pci_device_id provided by <linux/pci.h> work with
const pci_device_id. So mark the non-const structs as const.

File size before:
   text	   data	    bss	    dec	    hex	filename
   2610	    304	      8	   2922	    b6a	sound/hda/hdac_i915.o

File size After adding 'const':
   text	   data	    bss	    dec	    hex	filename
   2674	    240	      8	   2922	    b6a	sound/hda/hdac_i915.o
Signed-off-by: NArvind Yadav <arvind.yadav.cs@gmail.com>
Signed-off-by: NTakashi Iwai <tiwai@suse.de>

sound/hda/hdac_i915.c

@@ -336,7 +336,7 @@ EXPORT_SYMBOL_GPL(snd_hdac_i915_register_notifier);
 /* check whether intel graphics is present */
 static bool i915_gfx_present(void)
 {
-	static struct pci_device_id ids[] = {
+	static const struct pci_device_id ids[] = {
 		{ PCI_DEVICE(PCI_VENDOR_ID_INTEL, PCI_ANY_ID),
 		  .class = PCI_BASE_CLASS_DISPLAY << 16,
 		  .class_mask = 0xff << 16 },