libmodbus: ported recipe from classic and updated

* based on recipe by Radoslav Kolev which was in classic
 * updated to latest released version 3.0.2

 v2:
 * drop git version of recipe
 * drop no longer used PRIORITY

 v3:
 * drop PR = "r0"

Signed-off-by: Andrea Galbusera <gizero@gmail.com>
Signed-off-by: Koen Kooi <koen@dominion.thruhere.net>