staging: brcm80211: removed two fullmac sparse spinlock warnings

By deleting three redundant functions. The spinlock was related to
event queue operation. Event queue data members were also renamed
to make their function more clear.

Reported-by: Johannes Berg <johannes@sipsolutions.net>
Reviewed-by: Arend van Spriel <arend@broadcom.com>
Reviewed-by: Franky Lin <frankyl@broadcom.com>
Signed-off-by: Franky Lin <frankyl@broadcom.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>