ath9k_htc: Remove unused WMI commands

WMI_TGT_TXQ_ENABLE_CMDID
WMI_HOST_ATTACH
WMI_DEBUG_INFO_CMDID
WMI_BEACON_UPDATE_CMDID
WMI_RESET_CMDID
WMI_RX_LINK_CMDID
WMI_STOP_DMA_RECV_CMDID

Signed-off-by: Sujith Manoharan <Sujith.Manoharan@atheros.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>