brcmfmac: assure p2pdev is unregistered upon driver unload

brcmfmac: assure p2pdev is unregistered upon driver unload

When unloading the driver with a p2pdev interface it resulted in
a warning upon calling wiphy_unregister() and subsequently a crash
in the driver. This patch assures the p2pdev is unregistered calling
unregister_wdev() before doing the wiphy_unregister().

Reviewed-by: Hante Meuleman <meuleman@broadcom.com>
Reviewed-by: Franky (Zhenhui) Lin <frankyl@broadcom.com>
Reviewed-by: Pieter-Paul Giesberts <pieterpg@broadcom.com>
Signed-off-by: Arend van Spriel <arend@broadcom.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>