[media] ts2020: Add a comment about lifetime of on-stack pdata in ts2020_attach()

ts2020_attach() allocates a variable pdata on the stack and then passes a
pointer to it to i2c_new_device() which stashes the pointer in persistent
structures.

Add a comment to the effect that this isn't actually an error because the
contents of the variable are only used in ts2020_probe() and this is only
called ts2020_attach()'s stack frame exists.

Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Antti Palosaari <crope@iki.fi>
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>

drivers/media/dvb-frontends/ts2020.c

@@ -363,6 +363,8 @@ struct dvb_frontend *ts2020_attach(struct dvb_frontend *fe,
 {
 	struct i2c_client *client;
 	struct i2c_board_info board_info;
+
+	/* This is only used by ts2020_probe() so can be on the stack */
 	struct ts2020_config pdata;
 
 	memcpy(&pdata, config, sizeof(pdata));