dvbdev: fix illegal re-usage of fileoperations struct

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.

(backported from commit b61901024776b25ce7b8edc31bb1757c7382a88e)

Signed-off-by: Marcel Siegert <mws@linuxtv.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>
Signed-off-by: Michael Krufky <mkrufky@linuxtv.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>