While dvb_tuner_ops already has dedicated suspend and resume callbacks,
dvb_frontend_ops currently does not have them. Add those callbacks and
use them for suspend and resume. If they are not set, the old behavior
of calling sleep or init is used.

This allows dvb_frontend drivers to handle resume differently from init,
and suspend differently from sleep. No change is required for drivers
not needing this functionality.

Link: https://lore.kernel.org/linux-media/20210418001204.7453-2-kernel@tuxforce.de

Cc: Lukas Middendorf <kernel@tuxforce.de>, Antti Palosaari <crope@iki.fi>, Mauro Carvalho Chehab <mchehab@kernel.org>, Luis Chamberlain <mcgrof@kernel.org>
Signed-off-by: Lukas Middendorf <kernel@tuxforce.de>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>