coccicheck: Allow the user to give a V= (verbose) argument

Do not run with verbosity on/off depending on the ONLINE variable,
which gets set with C=1 or C=2, but allow the user to set the
verbosity using kernel default make V= paramemter.
Verbosity is off by default now.

Signed-off-by: Bernd Schubert <bernd.schubert@itwm.fraunhofer.de>
CC: Julia Lawall <Julia.Lawall@lip6.fr>
Acked-by: Nicolas Palix <nicolas.palix@imag.fr>
Signed-off-by: Michal Marek <mmarek@suse.cz>