wifi: brcmfmac: change cfg80211_set_channel() name and signature

The function cfg80211_set_channel() is an static function in brcmfmac
but the name is misleading. Hence rename it with 'brcmf' prefix. Also
changing the parameters to avoid additional conversions.

Signed-off-by: Arend van Spriel <arend.vanspriel@broadcom.com>
Signed-off-by: Kalle Valo <kvalo@kernel.org>
Link: https://lore.kernel.org/r/20230103124117.271988-4-arend.vanspriel@broadcom.com