wcn36xx: set default BTLE coexistence config

If the value for the firmware configuration parameters
BTC_STATIC_LEN_LE_BT and BTC_STATIC_LEN_LE_WLAN are not set the duty
cycle between BT and WLAN is such that if BT (including BLE) is active
WLAN gets 0 bandwidth. When tuning these parameters having a too high
value for WLAN means that BLE performance degrades.
The "sweet" point of roughly half of the maximal values was empirically
found to achieve a balance between BLE and Wi-Fi coexistence
performance.

Signed-off-by: Eyal Ilsar <eilsar@codeaurora.org>
Signed-off-by: Ramon Fried <rfried@codeaurora.org>
Acked-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Signed-off-by: Kalle Valo <kvalo@qca.qualcomm.com>