vfs: don't overwrite errno by a hard coded ENOENT

Calling "open" in CHECK_AND_CALL sets a perfectly correct errno.
There is no need to overwrite that with a value of ENOENT, since doing
so hides lower level errors like EIO.

Closes https://github.com/espressif/esp-idf/pull/8036

components/vfs/vfs.c

@@ -399,7 +399,7 @@ int esp_vfs_open(struct _reent *r, const char * path, int flags, int mode)
         __errno_r(r) = ENOMEM;
         return -1;
     }
-    __errno_r(r) = ENOENT;
+    __errno_r(r) = errno;
     return -1;
 }