Revert "Edited VFSFileImpl::read to use both read/fread (espressif#6456)"

This reverts commit 7b89b39.

Author: Jason2866

Diff for: libraries/FS/src/vfs_api.cpp

@@ -13,12 +13,9 @@
 // limitations under the License.
 
 #include "vfs_api.h"
-#include <stdio_ext.h>
 
 using namespace fs;
 
-#define READ_SIZE_SWITCH 128    //swithc to read func when read size > 128bytes
-
 FileImplPtr VFSImpl::open(const char* fpath, const char* mode, const bool create)
 {
     if(!_mountpoint) {
@@ -377,28 +374,7 @@ size_t VFSFileImpl::read(uint8_t* buf, size_t size)
         return 0;
     }
 
-    //ERASE BYTEBUFFER and use read when size > READ_SIZE_SWITCH always
-    if(size > READ_SIZE_SWITCH)
-    {
-        //check some data in buffer exists –> clear buffer and move pointer to deleted data
-        size_t bytesinbuf = __fpending(_f);
-        if (bytesinbuf && (bytesinbuf != 128))  //buffer lenght is 128 bytes
-        {
-            fpurge(_f);
-            lseek(fileno(_f),(-128+bytesinbuf),SEEK_CUR);
-        }
-
-        int res = ::read(fileno(_f), buf, size);
-        if (res < 0) {
-            // an error occurred
-            return 0;
-        }
-        return res;
-    }
-    else
-    {
-        return fread(buf, 1, size, _f);
-    }
+    return fread(buf, 1, size, _f);
 }
 
 void VFSFileImpl::flush()