Bluetooth: controller: Fix ULL LLL execution priority selection

Fix Kconfig default values for ULL and LLL execution
priorities that caused build warnings when ranges changes
based on other priority values being selected.

Signed-off-by: Vinayak Kariappa Chettimada <vich@nordicsemi.no>

subsys/bluetooth/controller/Kconfig

@@ -481,7 +481,7 @@ config BT_CTLR_ULL_HIGH_PRIO
 	int "Upper Link Layer High IRQ priority"
 	range BT_CTLR_LLL_PRIO 3 if SOC_SERIES_NRF51X
 	range BT_CTLR_LLL_PRIO 6 if SOC_SERIES_NRF52X
-	default 0
+	default BT_CTLR_LLL_PRIO
 	help
 	  The interrupt priority for Ticker's Worker IRQ and Upper Link Layer
 	  higher priority functions.
@@ -490,7 +490,7 @@ config BT_CTLR_ULL_LOW_PRIO
 	int "Upper Link Layer Low IRQ priority"
 	range BT_CTLR_ULL_HIGH_PRIO 3 if SOC_SERIES_NRF51X
 	range BT_CTLR_ULL_HIGH_PRIO 6 if SOC_SERIES_NRF52X
-	default 0
+	default BT_CTLR_ULL_HIGH_PRIO
 	help
 	  The interrupt priority for Ticker's Job IRQ and Upper Link Layer
 	  lower priority functions.
@@ -499,7 +499,7 @@ config BT_CTLR_LOWEST_PRIO
 	int "Link Layer Lowest IRQ priority"
 	range BT_CTLR_ULL_LOW_PRIO 3 if SOC_SERIES_NRF51X
 	range BT_CTLR_ULL_LOW_PRIO 6 if SOC_SERIES_NRF52X
-	default 0
+	default BT_CTLR_ULL_LOW_PRIO
 	help
 	  The interrupt priority for RNG and other non-critical functions.