[LTP] [PATCH 1/1] if-mtu-change.sh: Add max packet size detection for IPv4

[Petr Vorel]

Hi Alexey,

> > -		tst_ping -s "1 1000 65507"
> > +		tst_ping -s "1 1000 $MAX_PACKET_SIZE"

> tst_ping -s "1 $((mtu / 2)) $mtu $MAX_PACKET_SIZE"?
Thinking about this twice: adding forth size prolong test a bit (test is already
quite slow. But it makes sense to me to test all 4 variants.

Kind regards,
Petr