elm: fix legacy callback names.
Summary:
this patch is fix of D10240.
there are few mischanges on callback names,
so fix it orginal legacy names,
SCROLL_CHANGED = "scroll"
SCROLL_ANIM_START = "scroll,anim,start"
SCROLL_ANIM_STOP = "scroll,anim,stop"
SCROLL_DRAG_START = "scroll,drag,start"
SCROLL_DRAG_STOP = "scroll,drag,stop"
Reviewers: bu5hm4n, eagleeye, akanad
Reviewed By: eagleeye
Subscribers: cedric, #reviewers, #committers
Tags: #efl
Differential Revision: https://phab.enlightenment.org/D10332