[nrf fromtree] bluetooth: Add Kconfig for LE Connection Subrating

Add separate Kconfig to be used by the host LE Subrating implementation.

Signed-off-by: Aleksandar Stanoev <[email protected]>
(cherry picked from commit c417bd2)

Author: alexstanoev-nordic

subsys/bluetooth/Kconfig

@@ -181,6 +181,14 @@ config BT_PATH_LOSS_MONITORING
 	  Enable support for LE Path Loss Monitoring feature that is defined in the
 	  Bluetooth Core specification, Version 5.4 | Vol 6, Part B, Section 4.6.32.
 
+config BT_SUBRATING
+	bool "LE Connection Subrating [EXPERIMENTAL]"
+	select EXPERIMENTAL
+	depends on !BT_CTLR || BT_CTLR_SUBRATING_SUPPORT
+	help
+	  Enable support for LE Connection Subrating feature that is defined in the
+	  Bluetooth Core specification, Version 5.4 | Vol 6, Part B, Section 4.6.35.
+
 endif # BT_CONN
 
 rsource "Kconfig.iso"

subsys/bluetooth/controller/Kconfig

@@ -1025,6 +1025,7 @@ config BT_CTLR_SUBRATING
 	bool "LE Connection Subrating"
 	depends on BT_CTLR_SUBRATING_SUPPORT
 	select BT_CTLR_SET_HOST_FEATURE
+	default y if BT_SUBRATING
 	help
 	  Enable support for Bluetooth v5.3 LE Connection Subrating
 	  in the Controller.