Change M27 argument from L to P as that makes more sense (path vs LFN))

Firmware/Marlin_main.cpp

@@ -5818,7 +5818,7 @@ if(eSoundMode!=e_SOUND_MODE_SILENT)
 	### M27 - Get SD status <a href="https://reprap.org/wiki/G-code#M27:_Report_SD_print_status">M27: Report SD print status</a>
     */
     case 27:
-      card.getStatus(code_seen('L'));
+      card.getStatus(code_seen('P'));
       break;
 
     /*!

Firmware/cardreader.cpp

@@ -502,7 +502,7 @@ uint32_t CardReader::getFileSize()
 	return filesize;
 }
 
-void CardReader::getStatus(bool arg_L)
+void CardReader::getStatus(bool arg_P)
 {
     if (isPrintPaused)
     {
@@ -513,7 +513,7 @@ void CardReader::getStatus(bool arg_L)
     }
     else if (sdprinting)
     {
-        if (arg_L)
+        if (arg_P)
         {
             SERIAL_PROTOCOL('/');
             for (uint8_t i = 0; i < getWorkDirDepth(); i++)

Firmware/cardreader.h

@@ -26,7 +26,7 @@ public:
   void release();
   void startFileprint();
   uint32_t getFileSize();
-  void getStatus(bool arg_L);
+  void getStatus(bool arg_P);
   void printingHasFinished();
 
   void getfilename(uint16_t nr, const char* const match=NULL);