elm scrollable: return correct values from post event callbacks

elm scrollable: return correct values from post event callbacks

This fixes a small bug in my old patch 248b6beeee1e238

commit f1163107574a150cda7d1ef5e34f005e58b9680d
Author: Mike Blumenkrantz <zmike@osg.samsung.com>
Date:   Thu Nov 3 11:42:26 2016 -0400

   elm scrollable: return correct values from post event callbacks

   post event callbacks must return 0 to stop processing when an event is
   consumed, and 1 when processing should continue. this is the only place in
   all of efl which used this functionality, and it did so incorrectly.

   @fix

   ref 248b6beeee1e2387176e3abec7176e916175f12a
   ref D2393

Change-Id: I943779d2a005637e470f9fc40d9cb15782b14b20
Signed-off-by: Amitesh Singh <amitesh.sh@samsung.com>