brcmfmac: remove conversational comment

Removing a comment that was only useful during the review of
the change that introduced it and which should never have been
submitted.

Reviewed-by: Hante Meuleman <meuleman@broadcom.com>
Signed-off-by: Arend van Spriel <arend@broadcom.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>