bbs: bump crosscompiler to crosstool-ng 1.23-git-872341e for HD51 hardware platform
bbs: make variable FLAVOUR selectable by bbs config and add the possibility to build neutrino-mp for nevis hardware platform
linuxkernel-hd51.mk: add dvbs2x kernel patch
neutrino.mk: make variable LH_SRC selectable by bbs config and rename it to LH_SOURCE
neutrino.mk: adjust creation of image information to current neutrino-hd version
bbs: drop default BOXMODEL 'neo' and show an error message instead
drivers-hd51.mk: bump drivers to 20191120 for HD51 hardware platform
neutrino.mk: fix libstb-hal build for HD51 hardware platform