brcmfmac: add missing header dependencies

We get 1 warning when building kernel with W=1:

drivers/net/wireless/broadcom/brcm80211/brcmfmac/tracepoint.c:23:6: warning: no previous prototype for '__brcmf_err' [-Wmissing-prototypes]

In fact, this function is declared in brcmfmac/debug.h, so this patch
adds missing header dependencies.

Signed-off-by: Baoyou Xie <baoyou.xie@linaro.org>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>