media: cxd2820r: remove unused cxd2820r_debug declaration

cxd2820r_debug has been removed since
commit 75aeafc9 ("[media] cxd2820r: switch to Kernel
dev_* logging"), so remove it.
Signed-off-by: Gaosheng Cui <cuigaosheng1@huawei.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>

drivers/media/dvb-frontends/cxd2820r_priv.h

@@ -52,8 +52,6 @@ struct cxd2820r_priv {
 
 /* cxd2820r_core.c */
 
-extern int cxd2820r_debug;
-
 int cxd2820r_gpio(struct dvb_frontend *fe, u8 *gpio);
 
 int cxd2820r_wr_reg_val_mask_tab(struct cxd2820r_priv *priv,