brcmfmac: Remove duplicate struct declaration

struct brcmf_bus is declared twice. One has been declared
at 37th line. Remove the duplicate.
Signed-off-by: Wan Jiabing <wanjiabing@vivo.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
Link: https://lore.kernel.org/r/20210331023557.2804128-2-wanjiabing@vivo.com

drivers/net/wireless/broadcom/brcm80211/brcmfmac/debug.h

@@ -112,7 +112,6 @@ do {									\
 
 extern int brcmf_msg_level;
 
-struct brcmf_bus;
 struct brcmf_pub;
 #ifdef DEBUG
 struct dentry *brcmf_debugfs_get_devdir(struct brcmf_pub *drvr);