V4L/DVB (5321): Saa7134-dvb: initialize the dvb frontend in dvb_init

The hardware is completely initialized afterwards, especially the
tda10046 has its firmware - which is also necessary in analog mode
of some hybrid boards.
Calling the sleep function afterwards saves power and definitely puts
hybrid boards into analog mode without additional code elsewere.

Signed-off-by: Hartmut Hackmann <hartmut.hackmann@t-online.de>
Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>