Merge pull request #3913 from pan-/NRF51-fix-sleep-override

[NRF51822] Fix reference to sleep in hal_patch override

Author: 0xc0170

features/FEATURE_BLE/targets/TARGET_NORDIC/TARGET_MCU_NRF51822/hal_patch/sleep.c

@@ -66,6 +66,6 @@ void hal_sleep(void)
 
 void hal_deepsleep(void)
 {
-    sleep();
+    hal_sleep();
     //   NRF_POWER->SYSTEMOFF=1;
 }