qcacmn: resolve time out issue for get tx power

Currently, clearing the TYPE_CONNECTION_TX_POWER is
doing after the callback get_tx_power_cb.

Timeout issue happens because:
1\ the callback get_tx_power_cb is interrupted
   after invoking osif_request_complete.
2\ __wlan_hdd_cfg80211_get_txpower is called again
   and setting TYPE_CONNECTION_TX_POWER.
3\ the callback is rescheduled and clears the bit
   TYPE_CONNECTION_TX_POWER.
4\ Because the bit TYPE_CONNECTION_TX_POWER is cleared,
   and callback won't be invoke.

Change-Id: I6a5b155d2274551b637dc22095d292a70f836700
CRs-Fixed: 2418587