drm/i915/skl: Removed assert for csr-fw-loading check during disabling dc6

As during disabling dc6 no need to check for csr firmware
loading status, so removed the assert call (Requested by Damien).

Cc: Damien Lespiau <damien.lespiau@intel.com>
Signed-off-by: NAnimesh Manna <animesh.manna@intel.com>
Signed-off-by: NImre Deak <imre.deak@intel.com>
Tested-by: Daniel Stone <daniels@collabora.com> # SKL
Signed-off-by: NJani Nikula <jani.nikula@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1446069547-24760-14-git-send-email-imre.deak@intel.com

drivers/gpu/drm/i915/intel_runtime_pm.c

@@ -553,7 +553,6 @@ static void assert_can_disable_dc6(struct drm_i915_private *dev_priv)
 	if (dev_priv->power_domains.initializing)
 		return;
 
-	assert_csr_loaded(dev_priv);
 	WARN_ONCE(!(I915_READ(DC_STATE_EN) & DC_STATE_EN_UPTO_DC6),
 		  "DC6 already programmed to be disabled.\n");
 }