ath10k: define ath10k_debug_start/_stop as static inline

Otherwise if CONFIG_ATH10K_DEBUGFS won't be set we will
end up with multiple definitions and compilation failure
in each place the header is included.

Signed-off-by: Bartosz Markowski <bartosz.markowski@tieto.com>
Signed-off-by: Kalle Valo <kvalo@qca.qualcomm.com>
diff --git a/drivers/net/wireless/ath/ath10k/debug.h b/drivers/net/wireless/ath/ath10k/debug.h
index 9c442a8..376a56b 100644
--- a/drivers/net/wireless/ath/ath10k/debug.h
+++ b/drivers/net/wireless/ath/ath10k/debug.h
@@ -52,12 +52,12 @@
 				    struct wmi_stats_event *ev);
 
 #else
-int ath10k_debug_start(struct ath10k *ar)
+static inline int ath10k_debug_start(struct ath10k *ar)
 {
 	return 0;
 }
 
-void ath10k_debug_stop(struct ath10k *ar)
+static inline void ath10k_debug_stop(struct ath10k *ar)
 {
 }