staging: vt6656: rename INTvWorkItem to vnt_int_start_interrupt

This function does run as work item, it starts interrupts from the
device.

Rename to vnt_int_start_interrupt

Signed-off-by: Malcolm Priestley <tvboxspy@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>