Revert "Slider: Fix "Binding loop detected" warning"

This reverts commit 1283dffcae90ace0cd97e10f28082318a3049271

As Tomasz pointed out, this causes a regression when setting value so we need to revise.

Change-Id: I965b815b14b7ec7497e1a09d42fd973c74759f2b
Reviewed-by: Caroline Chao <caroline.chao@digia.com>