[nrf fromtree] Bluetooth: Controller: Replace WFE use with k_cpu_atomic_idle()

Replace the use of WFE with Zephyr kernel supplied
k_cpu_atomic_idle() interface.

Signed-off-by: Vinayak Kariappa Chettimada <[email protected]>
(cherry picked from commit 3c0c9ac)
Signed-off-by: Andrzej Głąbek <[email protected]>

Author: cvinayak

subsys/bluetooth/controller/ll_sw/nordic/hal/nrf5/cpu.h

@@ -5,25 +5,11 @@
  * SPDX-License-Identifier: Apache-2.0
  */
 
+#include <zephyr/kernel.h>
+
 static inline void cpu_sleep(void)
 {
-#if defined(CONFIG_CPU_CORTEX_M0) || \
-	defined(CONFIG_CPU_CORTEX_M4) || \
-	defined(CONFIG_CPU_CORTEX_M33) || \
-	defined(CONFIG_SOC_SERIES_BSIM_NRFXX)
-	/*
-	 * To guarantee waking up from the event, the
-	 * SEV-On-Pend feature must be enabled (enabled
-	 * during ARCH initialization).
-	 *
-	 * DSB is recommended by spec before WFE (to
-	 * guarantee completion of memory transactions)
-	 */
-	__DSB();
-	__WFE();
-	__SEV();
-	__WFE();
-#endif
+	k_cpu_atomic_idle(irq_lock());
 }
 
 static inline void cpu_dmb(void)