Merge pull request #6598 from embeddedartists/lpc4088_hardfault_fix

LPC4088: Fix hardfault occuring after power-cycle

Author: Cruz Monrreal

targets/TARGET_NXP/TARGET_LPC408X/sleep.c

@@ -19,12 +19,13 @@
 
 void hal_sleep(void) {
     LPC_SC->PCON = 0x0;
-    
+
     // SRC[SLEEPDEEP] set to 0 = sleep
     SCB->SCR &= ~SCB_SCR_SLEEPDEEP_Msk;
-    
+
     // wait for interrupt
     __WFI();
+    __NOP();
 }
 
 /*