drm/i915: don't schedule force_wake_timer at gen6_read

So far force_wake_timer was only used by gen6_gt_force_wake_put. Since
we always had balanced gen6_gt_force_wake_get/put calls, we could
guarantee balanced calls to intel_runtime_pm_get/put.

Commit 8232644, "drm/i915: Convert
the forcewake worker into a timer func" started scheduling the
force_wake_timer at gen6_read, which resulted in an unbalanced
runtime_pm refcount.

So this commit just reverts to the old behavior until we can find a
proper way to used delayed force_wake from the register read/write
macros without leaving the runtime_pm refcounts unbalanced and without
runtime suspending the driver while forcewake is active.

Testcase: igt/pm_pc8/rte
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=76544
Signed-off-by: Paulo Zanoni <paulo.r.zanoni@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/intel_uncore.c

@@ -550,11 +550,12 @@ gen6_read##x(struct drm_i915_private *dev_priv, off_t reg, bool trace) { \
 	    NEEDS_FORCE_WAKE((dev_priv), (reg))) { \
 		dev_priv->uncore.funcs.force_wake_get(dev_priv, \
 						      FORCEWAKE_ALL); \
-		dev_priv->uncore.forcewake_count++; \
-		mod_timer_pinned(&dev_priv->uncore.force_wake_timer, \
-				 jiffies + 1); \
+		val = __raw_i915_read##x(dev_priv, reg); \
+		dev_priv->uncore.funcs.force_wake_put(dev_priv, \
+						      FORCEWAKE_ALL); \
+	} else { \
+		val = __raw_i915_read##x(dev_priv, reg); \
 	} \
-	val = __raw_i915_read##x(dev_priv, reg); \
 	REG_READ_FOOTER; \
 }