drivers/gpu/drm/i915/i915_irq.c: fix warning

drivers/gpu/drm/i915/i915_irq.c: In function 'i915_disable_pipestat':
drivers/gpu/drm/i915/i915_irq.c:101: warning: control may reach end of non-void function 'i915_pipestat' being inlined

Cc: Dave Airlie <airlied@linux.ie>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

drivers/gpu/drm/i915/i915_irq.c

@@ -78,7 +78,7 @@ i915_pipestat(int pipe)
 		return PIPEASTAT;
 	if (pipe == 1)
 		return PIPEBSTAT;
-	BUG_ON(1);
+	BUG();
 }
 
 void