lib: export vsscanf

The function was missing from exports, even though it loooks like the
intent of the implementation in sscanf.c was to have it exported.

Signed-off-by: Samuel Dionne-Riel <samuel@dionne-riel.com>
Cc: Simon Glass <sjg@chromium.org>
Reviewed-by: Simon Glass <sjg@chromium.org>
diff --git a/include/vsprintf.h b/include/vsprintf.h
index b474630..8bfafa0 100644
--- a/include/vsprintf.h
+++ b/include/vsprintf.h
@@ -308,6 +308,14 @@
 void str_to_upper(const char *in, char *out, size_t len);
 
 /**
+ * vsscanf - Unformat a buffer into a list of arguments
+ * @buf:	input buffer
+ * @fmt:	format of buffer
+ * @args:	arguments
+ */
+int vsscanf(const char *inp, char const *fmt0, va_list ap);
+
+/**
  * sscanf - Unformat a buffer into a list of arguments
  * @buf:	input buffer
  * @fmt:	formatting of buffer