brcmfmac: fix double free of p2pdev interface

When freeing the driver ifp pointer it should also be removed from
the driver interface list, which is what brcmf_remove_interface()
does. Otherwise, the ifp pointer will be freed twice triggering
a kernel oops.

Fixes: f37d69a4 ("brcmfmac: free ifp for non-netdev interface in p2p module")
Reviewed-by: Pieter-Paul Giesberts <pieterpg@broadcom.com>
Reviewed-by: Hante Meuleman <meuleman@broadcom.com>
Signed-off-by: Arend van Spriel <arend@broadcom.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>