staging: rtl8821ae: deal with unused functions in halbtc8723b1ant.c

This commit fixes the compiler -Wunused-function warning. Most of the
unused functions were removed however for a few of them it was enough
to put #define around them.

Removed symbols:

    halbtc8723b1ant_rf_shrink
    halbtc8723b1ant_dac_swing
    halbtc8723b1ant_adc_backoff
    halbtc8723b1ant_agc_table
    halbtc8723b1ant_coex_alloff
    halbtc8723b1ant_ps_tdma_type_by_wifi_rssi
    halbtc8723b1ant_set_sw_rf_rx_lpf_corner
    halbtc8723b1ant_set_sw_full_time_dac_swing
    halbtc8723b1ant_set_adc_backoff
    halbtc8723b1ant_set_agc_table
    halbtc8723b1ant_set_dac_swing_reg

Conditionally compiled symbols:

    halbtc8723b1ant_bt_auto_report
    halbtc8723b1ant_set_bt_auto_report
    halbtc8723b1ant_action_wifi_only
    halbtc8723b1ant_monitor_bt_enable_disable

Signed-off-by: Konrad Zapalowicz <bergo.torino@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>