drm/i915: Use for_each_power_domain() in i915_power_domain_info()

Macro seems to do exactly the same thing.
Signed-off-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Link: http://patchwork.freedesktop.org/patch/msgid/1486559530-15141-1-git-send-email-joonas.lahtinen@linux.intel.com

drivers/gpu/drm/i915/i915_debugfs.c

@@ -2822,15 +2822,10 @@ static int i915_power_domain_info(struct seq_file *m, void *unused)
 		seq_printf(m, "%-25s %d\n", power_well->name,
 			   power_well->count);
 
-		for (power_domain = 0; power_domain < POWER_DOMAIN_NUM;
-		     power_domain++) {
-			if (!(BIT(power_domain) & power_well->domains))
-				continue;
-
+		for_each_power_domain(power_domain, power_well->domains)
 			seq_printf(m, "  %-23s %d\n",
 				 intel_display_power_domain_str(power_domain),
 				 power_domains->domain_use_count[power_domain]);
-		}
 	}
 
 	mutex_unlock(&power_domains->lock);