brcmfmac: Remove unused macro.

This macro is used exactly nowhere in the code. Delete it.

Signed-off-by: Ian Molton <ian@mnementh.co.uk>
Reviewed-by: Arend van Spriel <arend.vanspriel@broadcom.com>
Signed-off-by: Arend van Spriel <arend.vanspriel@broadcom.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>