Better handling of DELAY_NS and DELAY_US (#10716)

Co-Authored-By: ejtagle <ejtagle@hotmail.com>

Marlin/src/HAL/HAL_LPC1768/SoftwareSerial.cpp

@@ -37,6 +37,7 @@
 //
 //#include <WInterrupts.h>
 #include "../../inc/MarlinConfig.h"
+#include "../Delay.h"
 #include <stdint.h>
 #include <stdarg.h>
 #include <Arduino.h>
@@ -78,28 +79,9 @@ static const DELAY_TABLE table[] = {
 // Private methods
 //
 
-#if 0
-/* static */
 inline void SoftwareSerial::tunedDelay(const uint32_t count) {
-
-  asm volatile(
-
-    "mov r3, %[loopsPerMicrosecond] \n\t" //load the initial loop counter
-    "1: \n\t"
-    "sub r3, r3, #1 \n\t"
-    "bne 1b \n\t"
-
-    ://empty output list
-    :[loopsPerMicrosecond] "r" (count)
-    :"r3", "cc" //clobber list
-  );
-
+  DELAY_US(count);
 }
-#else
-inline void SoftwareSerial::tunedDelay(const uint32_t count) {
-  delayMicroseconds(count);
-}
-#endif
 
 // This function sets the current object as the "listening"
 // one and returns true if it replaces another