wireless: TI wlxxx depends on MAC80211

wl12xx build fails with many undefined symbol errors when MAC80211
and CFG80211 are not enabled, so make WLCORE and WL12XX depend
on MAC80211 (which already depends on CFG80211).

Here are a few of the many build errors:

drivers/built-in.o: In function `wl1271_register_hw':
main.c:(.text+0x4197cd): undefined reference to `ieee80211_register_hw'
drivers/built-in.o: In function `wl1271_rx_streaming_timer':
main.c:(.text+0x419818): undefined reference to `ieee80211_queue_work'
drivers/built-in.o: In function `wl1271_flush_deferred_work':
main.c:(.text+0x419910): undefined reference to `ieee80211_rx'
main.c:(.text+0x419938): undefined reference to `ieee80211_tx_status'
drivers/built-in.o: In function `wl12xx_op_channel_switch':
main.c:(.text+0x419afc): undefined reference to `ieee80211_chswitch_done'
drivers/built-in.o: In function `wl1271_ssid_set':
drivers/built-in.o: In function `wl1271_event_process':
event.c:(.text+0x41fec4): undefined reference to `ieee80211_sched_scan_stopped'
event.c:(.text+0x41ff88): undefined reference to `ieee80211_cqm_rssi_notify'
event.c:(.text+0x42000d): undefined reference to `ieee80211_stop_rx_ba_session'
event.c:(.text+0x420048): undefined reference to `ieee80211_stop_rx_ba_session'
event.c:(.text+0x4200b8): undefined reference to `ieee80211_chswitch_done'
event.c:(.text+0x4201ae): undefined reference to `ieee80211_find_sta'
event.c:(.text+0x4201ba): undefined reference to `ieee80211_report_low_ack'
event.c:(.text+0x42021b): undefined reference to `ieee80211_connection_loss'
drivers/built-in.o: In function `wl1271_tx_complete_packet':
tx.c:(.text+0x4206a6): undefined reference to `ieee80211_get_hdrlen_from_skb'
drivers/built-in.o: In function `wl1271_tx_fill_hdr':
tx.c:(.text+0x4208ca): undefined reference to `ieee80211_hdrlen'
drivers/built-in.o: In function `wl1271_handle_tx_low_watermark':
(.text+0x420e25): undefined reference to `ieee80211_wake_queue'
drivers/built-in.o: In function `wl12xx_rearm_rx_streaming':
(.text+0x420ed9): undefined reference to `ieee80211_queue_work'
drivers/built-in.o: In function `wl1271_tx_work_locked':
(.text+0x421008): undefined reference to `ieee80211_free_txskb'
drivers/built-in.o: In function `wl1271_rx_status.clone.2':
rx.c:(.text+0x421593): undefined reference to `ieee80211_channel_to_frequency'
drivers/built-in.o: In function `wl1271_ps_filter_frames':
ps.c:(.text+0x421a41): undefined reference to `ieee80211_tx_status'

Signed-off-by: Randy Dunlap <rdunlap@xenotime.net>
Cc:	Luciano Coelho <coelho@ti.com>
Cc:	linux-wireless@vger.kernel.org
Cc:	"John W. Linville" <linville@tuxdriver.com>
Signed-off-by: Luciano Coelho <coelho@ti.com>