wl2_input: fix a problem that occurs in case of using both pointer/touch input devices

wl2_input: fix a problem that occurs in case of using both pointer/touch input devices

Summary:
if wl2_input logic gets a 'touch down' event from touch device,
input->focus.touch has set and it cause the logic handles every input as touch input
from that moment at _ecore_wl2_input_mouse_move_send function.
that is the reason why the patch(410c1f95879e46a5e52132662d4c43b74e95a251) has written for.

however, if there are multiple touch input devices,
clearing focus.touch variable without checking any conditions causes another problem.

I mean a case such as 'touch 1 down' -> 'touch 2 down' -> 'touch 1 up' -> 'touch 2 up'
at the moment 'touch 1 up' event executed, focus.touch would be cleared,
and 'touch 2 up' and following touch events will not be executed properly at the moment.

this patch counts a number of touch devices which are grabbing to clear focus.touch at proper time.

Reviewers: devilhorns

Reviewed By: devilhorns

Subscribers: cedric, #reviewers, #committers

Tags: #efl

Differential Revision: https://phab.enlightenment.org/D8787

Change-Id: I95b64df82f17069762aa93a60b0eb048805e5bac
Signed-off-by: Wonki Kim <wonki_.kim@samsung.com>