iwlagn: wifi/bt coex configuration sequence

bt config command need to send before the init calibration command,
driver need to let uCode know that calibrations are being performed now
in order to assure antenna is not being taken to BT use during radio/dsp
reads/writes

Also, bt_coex_priorty_table command need to be send right after the
bt_config_command during init sequence. Followed by bt coex envelope
command to initialize and prepare uCode bt state machine

Signed-off-by: Wey-Yi Guy <wey-yi.w.guy@intel.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>