Revert "Update error codes as per mbed-os/pull/6336"

This reverts commit ba4ff5c.

Author: Deepika

SDBlockDevice.cpp

@@ -142,13 +142,13 @@
 #include "mbed_debug.h"
 #include <errno.h>
 
-/* Required version: 5.9.0 and above */
+/* Required version: 5.8.0 and above */
 #if defined(    MBED_MAJOR_VERSION) && MBED_MAJOR_VERSION >= 5
-#if (MBED_VERSION < MBED_ENCODE_VERSION(5,9,0))
-#error "Incompatible mbed-os version detected! Required 5.9.0 and above"
+#if (MBED_VERSION < MBED_ENCODE_VERSION(5,8,0))
+#error "Incompatible mbed-os version detected! Required 5.8.0 and above"
 #endif
 #else
-#warning "mbed-os version 5.9.0 or above required"
+#warning "mbed-os version 5.8.0 or above required"
 #endif
 
 #ifndef MBED_CONF_SD_CMD_TIMEOUT

TESTS/filesystem/dirs/main.cpp

@@ -188,7 +188,7 @@ void test_directory_failures() {
         res = fs.mkdir("potato", 0777);
         TEST_ASSERT_EQUAL(-EEXIST, res);
         res = dir[0].open(&fs, "tomato");
-        TEST_ASSERT_EQUAL(-ENOTDIR, res);
+        TEST_ASSERT_EQUAL(-ENOENT, res);
         res = dir[0].open(&fs, "burito");
         TEST_ASSERT_NOT_EQUAL(0, res);
         res = file[0].open(&fs, "tomato", O_RDONLY);