staging: vchi: Get rid of flags argument in vchi_msg_hold()

All users are ignoring the flags argument. So for the sake of
simplicity delete it.

Signed-off-by: Nicolas Saenz Julienne <nsaenzjulienne@suse.de>
Link: https://lore.kernel.org/r/20200629150945.10720-19-nsaenzjulienne@suse.de


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>