Bluetooth: controller: Disable not implemented DF features

Set to disabled not yet implemented Direction Finding features.
The features will be enabled by default when they are implemented.

Signed-off-by: Piotr Pryga <piotr.pryga@nordicsemi.no>
diff --git a/subsys/bluetooth/controller/Kconfig.df b/subsys/bluetooth/controller/Kconfig.df
index 01cae80..98cf808 100644
--- a/subsys/bluetooth/controller/Kconfig.df
+++ b/subsys/bluetooth/controller/Kconfig.df
@@ -77,7 +77,6 @@
 config BT_CTLR_DF_ANT_SWITCH_RX
 	bool "Enable antenna switching during CTE reception (AoA) feature"
 	depends on BT_CTLR_DF_CTE_RX && BT_CTLR_DF_ANT_SWITCH_2US_SUPPORT
-	default y
 	help
 	  Enable support for antenna switching during CTE reception.
 	  Also known as Angle of Arrival mode.