Merge pull request #2240 from leptun/MK3_fix_SD_workDirDepth

fix workDirDepth not reset after card init.

Firmware/cardreader.cpp

@@ -203,6 +203,7 @@ void CardReader::initsd()
   }
   workDir=root;
   curDir=&root;
+  workDirDepth = 0;
 
   #ifdef SDCARD_SORT_ALPHA
 	presort();