brcmfmac: use local iftype avoiding use-after-free of virtual interface

brcmfmac: use local iftype avoiding use-after-free of virtual interface

commit d77facb88448cdeaaa3adba5b9704a48ac2ac8d6 upstream.

A use-after-free was found using KASAN. In brcmf_p2p_del_if() the virtual
interface is removed using call to brcmf_remove_interface(). After that
the virtual interface instance has been freed and should not be referenced.
Solve this by storing the nl80211 iftype in local variable, which is used
in a couple of places anyway.

Reported-by: Daniel J Blueman <daniel@quora.org>
Reviewed-by: Hante Meuleman <hante.meuleman@broadcom.com>
Reviewed-by: Pieter-Paul Giesberts <pieter-paul.giesberts@broadcom.com>
Reviewed-by: Franky Lin <franky.lin@broadcom.com>
Signed-off-by: Arend van Spriel <arend.vanspriel@broadcom.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>