make taskPatrol accept Pos2D again

[commy2]

When merged this pull request will:

• title
• should fix: https://forums.bistudio.com/forums/topic/168277-cba-community-base-addons-arma-3/?page=42#comment-3185643 in a mission called "Battlezone"

The function accepted Pos2D at some point, but it was restricted to 3D in this PR: https://github.com/CBATeam/CBA_A3/pull/572/files

Pos2D works fine, because the alternate syntax getPos in taskPatrol accepts Pos2D (and ignores z anyway in Pos3D).

Test:

[this, getPosASL leader this select [0, 2], 50] call CBA_fnc_taskPatrol;

• works fine after this PR
• master:

 8:52:07 Error in expression <
... (edited out whitespace)
params [
["_group",grpNull,[grpNull,objN>
 8:52:07   Error position: <params [
["_group",grpNull,[grpNull,objN>
 8:52:07   Error 2 elements provided, 3 expected
 8:52:07 File \x\cba\addons\ai\fnc_taskPatrol.sqf [CBA_fnc_taskPatrol], line 1752

I have no idea why the line number is so wrong in the error.