package/lua: remove 5.2.x version

package/lua: remove 5.2.x version

At this time :
- Lua 5.3.5 will be the last one of its serie.
- Lua 5.4 is up coming (lua-5.4.0-work2 is already available).
- Lua 5.2.4 was released on 2015.
For various reasons in the Lua ecosystem, the Lua 5.1 will stay.
On BR, Lua 5.3 is the default version since 2016.02.

So, the serie which could be removed is the 5.2.x.
We could wait some days for other user feedback.

Note: see discussion when 5.3.x was introduced :
http://lists.busybox.net/pipermail/buildroot/2015-January/117638.html

Signed-off-by: Francois Perrad <francois.perrad@gadz.org>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>