drm/i915: fix intel_crtc_clock_get pipe reads after "cleanup cleanup"

Despite the fixes in 548f245b (drm/i915: fix per-pipe reads after
"cleanup"), we missed one neighbouring read that was mistakenly replaced
with the reg value in 9db4a9c7 (drm/i915: cleanup per-pipe reg usage).
This was preventing us from correctly determining the mode the BIOS left
the panel in for machines that neither have an OpRegion nor access to
the VBT, (e.g. the EeePC 700).
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Cc: Jesse Barnes <jbarnes@virtuousgeek.org>
Cc: stable@kernel.org
Reviewed-by: NJesse Barnes <jbarnes@virtuousgeek.org>
Signed-off-by: NKeith Packard <keithp@keithp.com>

drivers/gpu/drm/i915/intel_display.c

@@ -5603,9 +5603,9 @@ static int intel_crtc_clock_get(struct drm_device *dev, struct drm_crtc *crtc)
 	intel_clock_t clock;
 
 	if ((dpll & DISPLAY_RATE_SELECT_FPA1) == 0)
-		fp = FP0(pipe);
+		fp = I915_READ(FP0(pipe));
 	else
-		fp = FP1(pipe);
+		fp = I915_READ(FP1(pipe));
 
 	clock.m1 = (fp & FP_M1_DIV_MASK) >> FP_M1_DIV_SHIFT;
 	if (IS_PINEVIEW(dev)) {