brcmfmac: correct setting of WEP broadcast/unicast keys

brcmfmac: correct setting of WEP broadcast/unicast keys

The brcmf_add_keyext() is for setting per-station key for cipher
algorithms such as WPA1/WPA2 and should not be used to set
WEP broadcast/unicast keys. This patch fixes connect failure
problem with AP using 802.1x-WEP.

Reviewed-by: Hante Meuleman <meuleman@broadcom.com>
Reviewed-by: Arend van Spriel <arend@broadcom.com>
Reviewed-by: Pieter-Paul Giesberts <pieterpg@broadcom.com>
Reviewed-by: Franky (Zhenhui) Lin <frankyl@broadcom.com>
Signed-off-by: Daniel Kim <dekim@broadcom.com>
Signed-off-by: Arend van Spriel <arend@broadcom.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>