[nrf noup] Bluetooth: update experimental for qualification

Update Kconfig options for qualification:
 - Remove experimental on qualified feature.
 - Add experimental on unqualified feature.
 - BT_L2CAP_ECRED is not marked as experimental upstream and we qualify it
   downstream.

Signed-off-by: Joakim Andersson <[email protected]>
Signed-off-by: Trond Einar Snekvik <[email protected]>
Signed-off-by: Martí Bolívar <[email protected]>
Signed-off-by: Robert Lubos <[email protected]>
Signed-off-by: Dominik Ermel <[email protected]>
Signed-off-by: Ingar Kulbrandstad <[email protected]>
Signed-off-by: Torsten Rasmussen <[email protected]>
Signed-off-by: Herman Berget <[email protected]>
Signed-off-by: Tomasz Moń <[email protected]>
Signed-off-by: Théo Battrel <[email protected]>
(cherry picked from commit e5c30e3)

Author: joerchan

subsys/bluetooth/controller/Kconfig

@@ -143,10 +143,12 @@ config BT_CTLR
 	  the HAS_BT_CTLR option.
 
 config BT_LL_SW_SPLIT
-	bool "Software-based Bluetooth LE Link Layer"
+	bool "Software-based Bluetooth LE Link Layer [EXPERIMENTAL]"
 	default y
 	depends on DT_HAS_ZEPHYR_BT_HCI_LL_SW_SPLIT_ENABLED
 	select HAS_BT_CTLR
+	select EXPERIMENTAL
+	select ENTROPY_GENERATOR
 	help
 	  Use Zephyr software Bluetooth LE Link Layer ULL LLL split implementation.
 

subsys/bluetooth/host/Kconfig.l2cap

@@ -52,7 +52,7 @@ config BT_L2CAP_DYNAMIC_CHANNEL
 	  allowing the creation of dynamic L2CAP Channels.
 
 config BT_L2CAP_ECRED
-	bool "L2CAP Enhanced Credit Based Flow Control support"
+	bool "L2CAP Enhanced Credit Based Flow Control support [EXPERIMENTAL]"
 	depends on BT_L2CAP_DYNAMIC_CHANNEL
 	help
 	  This option enables support for LE Connection oriented Channels with