brcm80211: fmac: cleanup receive path using proper skb_queue functions

brcm80211: fmac: cleanup receive path using proper skb_queue functions

In the receive path there was still code using the next pointer to
access all packets in skb_queue. This patch fixes that.

Reported-by: Johannes Berg <johannes@sipsolutions.net>
Reviewed-by: Pieter-Paul Giesberts <pieterpg@broadcom.com>
Reviewed-by: Franky (Zhenhui) Lin <frankyl@broadcom.com>
Reviewed-by: Alwin Beukers <alwin@broadcom.com>
Signed-off-by: Arend van Spriel <arend@broadcom.com>
Signed-off-by: Franky Lin <frankyl@broadcom.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>