brcmfmac: handle IF event for P2P_DEVICE interface

The firmware notifies about interface changes through the IF event
which has a NO_IF flag that means host can ignore the event. This
behaviour was introduced in the driver by:

  commit 2ee8382f
  Author: Arend van Spriel <arend@broadcom.com>
  Date:   Sat Aug 10 12:27:24 2013 +0200

      brcmfmac: ignore IF event if firmware indicates it

It turns out that the IF event for the P2P_DEVICE also has this
flag set, but the event should not be ignored in this scenario.
The mentioned commit caused a regression in 3.12 kernel in creation
of the P2P_DEVICE interface.

Cc: <stable@vger.kernel.org> # 3.14, 3.16
Reviewed-by: Hante Meuleman <meuleman@broadcom.com>
Reviewed-by: Franky (Zhenhui) Lin <frankyl@broadcom.com>
Reviewed-by: Daniel (Deognyoun) Kim <dekim@broadcom.com>
Reviewed-by: Pieter-Paul Giesberts <pieterpg@broadcom.com>
Signed-off-by: Arend van Spriel <arend@broadcom.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>