ath10k: add new ATH10K_FW_FEATURE_BTCOEX_PARAM

This feature flag will be used for firmware to support BT-Coex feature
without reloading firmware via WMI pdev param. To support Bluetooth
coexistence pdev param, WMI_COEX_GPIO_SUPPORT of extended resource
config should be enabled always. This firmware IE is used to configure
WMI_COEX_GPIO_SUPPORT.

Signed-off-by: Rajkumar Manoharan <rmanohar@qti.qualcomm.com>
Signed-off-by: Kalle Valo <kvalo@qca.qualcomm.com>