[media] Rename set_frontend fops to set_frontend_legacy

Passing DVBv3 parameters to set_frontend is not fun, as the
core doesn't have any way to know if the driver is using the
v3 or v5 parameters. So, rename the callback and add a new
one to allow distinguish between a mixed v3/v5 paramenter call
from a pure v5 call.

After having all frontends to use the new way, the legacy
call can be removed.

Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
diff --git a/drivers/media/dvb/frontends/dib9000.c b/drivers/media/dvb/frontends/dib9000.c
index 660f806..c7b4910 100644
--- a/drivers/media/dvb/frontends/dib9000.c
+++ b/drivers/media/dvb/frontends/dib9000.c
@@ -2513,7 +2513,7 @@
 	.init = dib9000_wakeup,
 	.sleep = dib9000_sleep,
 
-	.set_frontend = dib9000_set_frontend,
+	.set_frontend_legacy = dib9000_set_frontend,
 	.get_tune_settings = dib9000_fe_get_tune_settings,
 	.get_frontend = dib9000_get_frontend,