drm/i915: fix wait_remaining_ms_from_jiffies

schedule_timeout_uninterruptible() takes jiffies not ms.

v2:
- ignore the overflow issue, the practical part of that should
  be solved instead in the caller (Chris)

Note that this issue was introduced in

commit dce56b3c62
Author: Paulo Zanoni <paulo.r.zanoni@intel.com>
Date:   Thu Dec 19 14:29:40 2013 -0200

drm/i915: save some time when waiting the eDP timings

I've accidentally merged the broken v4 version of the patch (where
Jani noticed the issue [1]) instead of the v5, which was fixed [2].

[1] http://mid.gmane.org/87fvpnkgyg.fsf@intel.com
[2] http://mid.gmane.org/1388778311-2020-1-git-send-email-przanoni@gmail.com

Signed-off-by: Imre Deak <imre.deak@intel.com>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
[danvet: Add admission of incompetence in the form of a note.]
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/i915_drv.h

@@ -2649,8 +2649,7 @@ timespec_to_jiffies_timeout(const struct timespec *value)
 static inline void
 wait_remaining_ms_from_jiffies(unsigned long timestamp_jiffies, int to_wait_ms)
 {
-	unsigned long target_jiffies, tmp_jiffies;
-	unsigned int remaining_ms;
+	unsigned long target_jiffies, tmp_jiffies, remaining_jiffies;
 
 	/*
 	 * Don't re-read the value of "jiffies" every time since it may change
@@ -2661,11 +2660,10 @@ wait_remaining_ms_from_jiffies(unsigned long timestamp_jiffies, int to_wait_ms)
 			 msecs_to_jiffies_timeout(to_wait_ms);
 
 	if (time_after(target_jiffies, tmp_jiffies)) {
-		remaining_ms = jiffies_to_msecs((long)target_jiffies -
-						(long)tmp_jiffies);
-		while (remaining_ms)
-			remaining_ms =
-				schedule_timeout_uninterruptible(remaining_ms);
+		remaining_jiffies = target_jiffies - tmp_jiffies;
+		while (remaining_jiffies)
+			remaining_jiffies =
+			    schedule_timeout_uninterruptible(remaining_jiffies);
 	}
 }