Makefile: No echoing for 'make help V=1'

It doesn't bring much to have echoing with "make help". Suppress it
unconditionally.

Signed-off-by: Greg Kurz <groug@kaod.org>
Message-Id: <160459122012.462591.8467906402712875729.stgit@bahia.lan>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>