rtw88: Remove duplicate include of coex.h

In commit fb8517f4fa ("rtw88: 8822c: add CFO tracking"),
"coex.h" was added here which caused the duplicate include.
Remove the later duplicate include.

Signed-off-by: Wan Jiabing <wanjiabing@vivo.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
Link: https://lore.kernel.org/r/20210430024951.33406-1-wanjiabing@vivo.com

drivers/net/wireless/realtek/rtw88/rtw8822c.c

@@ -17,7 +17,6 @@
 #include "util.h"
 #include "bf.h"
 #include "efuse.h"
-#include "coex.h"
 
 #define IQK_DONE_8822C 0xaa