drm/i915/bxt: Fix HDMI DPLL configuration

a277ca7dc0 should've been a no-functional-change commit, but it
removed the initialization of the dpll_hw_state for HDMI outputs,
resulting in state mismatches and a failed modeset with blank
screen. Fix this by reinstating the dpll_hw_state initialization.

v2:
- Make bxt_ddi_hdmi_set_dpll_hw_state() static.

Cc: Manasi Navare <manasi.d.navare@intel.com>
Cc: Ander Conselvan de Oliveira <ander.conselvan.de.oliveira@intel.com>
Cc: Durgadoss R <durgadoss.r@intel.com>
Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
Fixes: a277ca7dc0 ("drm/i915: Split bxt_ddi_pll_select()")
Signed-off-by: Imre Deak <imre.deak@intel.com>
Reviewed-by: Ander Conselvan de Oliveira <conselvan2@gmail.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1474901671-22719-1-git-send-email-imre.deak@intel.com

drivers/gpu/drm/i915/intel_dpll_mgr.c

@@ -1694,21 +1694,32 @@ bool bxt_ddi_dp_set_dpll_hw_state(int clock,
 	return bxt_ddi_set_dpll_hw_state(clock, &clk_div, dpll_hw_state);
 }
 
+static bool
+bxt_ddi_hdmi_set_dpll_hw_state(struct intel_crtc *intel_crtc,
+			       struct intel_crtc_state *crtc_state, int clock,
+			       struct intel_dpll_hw_state *dpll_hw_state)
+{
+	struct bxt_clk_div clk_div = { };
+
+	bxt_ddi_hdmi_pll_dividers(intel_crtc, crtc_state, clock, &clk_div);
+
+	return bxt_ddi_set_dpll_hw_state(clock, &clk_div, dpll_hw_state);
+}
+
 static struct intel_shared_dpll *
 bxt_get_dpll(struct intel_crtc *crtc,
 		struct intel_crtc_state *crtc_state,
 		struct intel_encoder *encoder)
 {
-	struct bxt_clk_div clk_div = {0};
-	struct intel_dpll_hw_state dpll_hw_state = {0};
+	struct intel_dpll_hw_state dpll_hw_state = { };
 	struct drm_i915_private *dev_priv = to_i915(crtc->base.dev);
 	struct intel_digital_port *intel_dig_port;
 	struct intel_shared_dpll *pll;
 	int i, clock = crtc_state->port_clock;
 
-	if (encoder->type == INTEL_OUTPUT_HDMI
-	    && !bxt_ddi_hdmi_pll_dividers(crtc, crtc_state,
-					  clock, &clk_div))
+	if (encoder->type == INTEL_OUTPUT_HDMI &&
+	    !bxt_ddi_hdmi_set_dpll_hw_state(crtc, crtc_state, clock,
+					    &dpll_hw_state))
 		return NULL;
 
 	if ((encoder->type == INTEL_OUTPUT_DP ||