ALSA: hda - Reduce ifdef CONFIG_SND_HDA_I915

We're providing dummy functions for CONFIG_SND_HDA_i915=n, thus ifdef
can be reduced.  (But hda_i915_init() has to be fixed to return zero.)

This automatically fixes a compile warning:
  sound/pci/hda/hda_intel.c: In function 'azx_probe_continue':
  sound/pci/hda/hda_intel.c:1966:1: warning: label 'i915_power_fail' defined but not used [-Wunused-label]

Reported-by: kbuild test robot <fengguang.wu@intel.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>

sound/pci/hda/hda_intel.c

@@ -1904,8 +1904,6 @@ static int azx_probe_continue(struct azx *chip)
 		if (pci->device != 0x0f04 && pci->device != 0x2284)
 			hda->need_i915_power = 1;
 
-
-#ifdef CONFIG_SND_HDA_I915
 		err = hda_i915_init(hda);
 		if (err < 0)
 			goto i915_power_fail;
@@ -1916,7 +1914,6 @@ static int azx_probe_continue(struct azx *chip)
 				"Cannot turn on display power on i915\n");
 			goto i915_power_fail;
 		}
-#endif
 	}
 
 	err = azx_first_init(chip);

sound/pci/hda/hda_intel.h

@@ -63,7 +63,7 @@ static inline int hda_display_power(struct hda_intel *hda, bool enable)
 static inline void haswell_set_bclk(struct hda_intel *hda) { return; }
 static inline int hda_i915_init(struct hda_intel *hda)
 {
-	return -ENODEV;
+	return 0;
 }
 static inline int hda_i915_exit(struct hda_intel *hda)
 {