i965: Fix byte vs. pixel unit mixup for aligned texture pitch.

I sincerely hope I don't manage to mess this up yet again...

Thanks again to Todd Merrill for pointing out the problem and testing the fix
on IRC.

src/mesa/drivers/dri/i965/intel_mipmap_tree.c

@@ -128,7 +128,7 @@ int intel_miptree_pitch_align (struct intel_context *intel,
 			       int pitch)
 {
    if (!mt->compressed)
-      pitch = (pitch * mt->cpp + 3) & ~3;
+      pitch = ((pitch * mt->cpp + 3) & ~3) / mt->cpp;
 
    return pitch;
 }