Fix for sdio_write_sectors

The issue was found by using f_mkdir("directory_name").
The function always returned FR_DISK_ERR due to an unhadled case in sdio_write_sectors().
According to this documentation: http://www.convict.lu/pdf/ProdManualSDCardv1.9.pdf#page=92 stop transmission command should be sent after writing multiple blocks.
This patch fixes this bug also adds a test case for it.

examples/fatfs/main.c

@@ -12,6 +12,7 @@
 
 #define CS_GPIO_PIN 2
 #define TEST_FILENAME "/test_loooong_filename.txt"
+#define TEST_DIRECTORYNAME "my_directory"
 #define TEST_CONTENTS "Hello! It's FatFs on esp8266 with ESP Open RTOS!"
 #define READBUF_SIZE 256
 #define DELAY_MS 3000
@@ -69,6 +70,19 @@ void check_fatfs()
     if (failed(f_chdrive(vol)))
         return;
 
+    // Create a directory if it not exists
+    FILINFO info;
+    if (failed(f_stat(TEST_DIRECTORYNAME, &info)) && info.fattrib & AM_DIR)
+    {
+      printf("f_mkdir (\"%s\")\n", TEST_DIRECTORYNAME);
+      if (failed(f_mkdir(TEST_DIRECTORYNAME)))
+          return;
+    }
+    else
+    {
+      printf("\"%s\" directory already exists\n", TEST_DIRECTORYNAME);
+    }
+
     FIL f;
     // Create test file
     printf("f_open(&f, \"%s\", FA_WRITE | FA_CREATE_ALWAYS)", TEST_FILENAME);