drm/i915: Simplify intel_sanitize_enable_ppgtt

Remove dead code around has_aliasing_ppgtt condition.
Suggested-by: NColin Ian King <colin.king@canonical.com>
Signed-off-by: NJoonas Lahtinen <joonas.lahtinen@linux.intel.com>
Cc: Colin Ian King <colin.king@canonical.com>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: NChris Wilson <chris@chris-wilson.co.uk>
Link: https://patchwork.freedesktop.org/patch/msgid/20171010143355.16577-1-joonas.lahtinen@linux.intel.com

drivers/gpu/drm/i915/i915_gem_gtt.c

@@ -135,11 +135,12 @@ static inline void i915_ggtt_invalidate(struct drm_i915_private *i915)
 int intel_sanitize_enable_ppgtt(struct drm_i915_private *dev_priv,
 			       	int enable_ppgtt)
 {
-	bool has_aliasing_ppgtt;
 	bool has_full_ppgtt;
 	bool has_full_48bit_ppgtt;
 
-	has_aliasing_ppgtt = dev_priv->info.has_aliasing_ppgtt;
+	if (!dev_priv->info.has_aliasing_ppgtt)
+		return 0;
+
 	has_full_ppgtt = dev_priv->info.has_full_ppgtt;
 	has_full_48bit_ppgtt = dev_priv->info.has_full_48bit_ppgtt;
 
@@ -149,9 +150,6 @@ int intel_sanitize_enable_ppgtt(struct drm_i915_private *dev_priv,
 		has_full_48bit_ppgtt = intel_vgpu_has_full_48bit_ppgtt(dev_priv);
 	}
 
-	if (!has_aliasing_ppgtt)
-		return 0;
-
 	/*
 	 * We don't allow disabling PPGTT for gen9+ as it's a requirement for
 	 * execlists, the sole mechanism available to submit work.
@@ -188,7 +186,7 @@ int intel_sanitize_enable_ppgtt(struct drm_i915_private *dev_priv,
 			return 2;
 	}
 
-	return has_aliasing_ppgtt ? 1 : 0;
+	return 1;
 }
 
 static int ppgtt_bind_vma(struct i915_vma *vma,