V4L/DVB (5244): Dvbdev: fix illegal re-usage of fileoperations struct
Arjan van de Ven <arjan@infradead.org> reported an illegal re-usage of
the fileoperations struct if more than one dvb device (e.g. frontend) is
present.
This patch fixes this issue.
It allocates a new fileoperations struct each time a device is
registered and copies the default template fileops.