media: dvb: Use WARM definition from identify_state()

Device should be either COLD or WARM.
This change only make usage of the existing definition.

Signed-off-by: Victor Toso <me@victortoso.com>
Signed-off-by: Sean Young <sean@mess.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>