brcmfmac: fix sparse warnings

Following sparse warning is fixed:
drivers/net/wireless/brcm80211/brcmfmac/wl_cfg80211.c:2518:21: warning: symbol 'brcmf_find_wpaie' was not declared. Should it be static?
drivers/net/wireless/brcm80211/brcmfmac/wl_cfg80211.c:3768:1: warning: symbol 'brcmf_set_management_ie' was not declared. Should it be static?

Signed-off-by: Franky Lin <frankyl@broadcom.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>