bluetooth: controller: Remove experimental from QoS Channel Survey

The QoS Channel Survey feature is not experimental in SDC anymore,
but the Kconfig entry was not updated accordingly.

Signed-off-by: Aleksandar Stanoev <aleksandar.stanoev@nordicsemi.no>

Author: alexstanoev-nordic

subsys/bluetooth/controller/Kconfig

@@ -108,7 +108,6 @@ config BT_CTLR_SDC_LLPM
 
 config BT_CTLR_SDC_QOS_CHANNEL_SURVEY
 	bool "Channel survey"
-	select EXPERIMENTAL
 	help
 	  Channel survey feature support