bluetooth: controller: Revised ticker for improved conflict resolution

Changed ticker behavior to resolve conflicts in ticker_worker instead of
in ticker_job. This allows better real-time slot allocation, as well as
allowing callbacks even if ticker node doesn't get air-time (for audio
stream housekeeping). A priority property now also allows prioritizing
one ticker node over others.
Compatibility mode enables lagacy ticker behavior if needed.

Signed-off-by: Morten Priess <mtpr@oticon.com>

subsys/bluetooth/controller/Kconfig

@@ -651,6 +651,15 @@ config BT_MAYFLY_YIELD_AFTER_CALL
 	  If set to 'n', all pending mayflies for callee are executed before
 	  yielding
 
+config BT_TICKER_COMPATIBILITY_MODE
+	bool "Ticker compatibility mode"
+	default y if SOC_SERIES_NRF51X
+	help
+	  This option enables legacy ticker scheduling which defers overlapping
+	  ticker node timeouts and thereby prevents ticker interrupts during
+	  radio RX/TX. Enabling this option disables the ticker priority- and
+	  'must expire' features.
+
 config BT_CTLR_USER_EXT
 	prompt "Enable proprietary extensions in Controller"
 	depends on BT_LL_SW_SPLIT