[media] dvb: don't cause missing symbols for drxk/tda18271c2dd

If those demods are unselected, but a bridge driver requires them,
produce a runtime message, instead of missing symbols.
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

drivers/media/dvb/frontends/drxk.h

@@ -29,7 +29,19 @@ struct drxk_config {
 	const char *microcode_name;
 };
 
+#if defined(CONFIG_DVB_DRXK) || (defined(CONFIG_DVB_DRXK_MODULE) \
+        && defined(MODULE))
 extern struct dvb_frontend *drxk_attach(const struct drxk_config *config,
 					struct i2c_adapter *i2c,
 					struct dvb_frontend **fe_t);
+#else
+static inline struct dvb_frontend *drxk_attach(const struct drxk_config *config,
+					struct i2c_adapter *i2c,
+					struct dvb_frontend **fe_t)
+{
+        printk(KERN_WARNING "%s: driver disabled by Kconfig\n", __func__);
+        return NULL;
+}
+#endif
+
 #endif

drivers/media/dvb/frontends/tda18271c2dd.h

@@ -2,4 +2,18 @@
 #define _TDA18271C2DD_H_
 struct dvb_frontend *tda18271c2dd_attach(struct dvb_frontend *fe,
 					 struct i2c_adapter *i2c, u8 adr);
+
+#if defined(CONFIG_DVB_TDA18271C2DD) || (defined(CONFIG_DVB_TDA18271C2DD_MODULE) \
+        && defined(MODULE))
+struct dvb_frontend *tda18271c2dd_attach(struct dvb_frontend *fe,
+					 struct i2c_adapter *i2c, u8 adr);
+#else
+static inline struct dvb_frontend *tda18271c2dd_attach(struct dvb_frontend *fe,
+					 struct i2c_adapter *i2c, u8 adr) {
+{
+        printk(KERN_WARNING "%s: driver disabled by Kconfig\n", __func__);
+        return NULL;
+}
+#endif
+
 #endif