cbfs: Move result variable into the struct

Move the result variable into the struct also, so that it can be used when
BSS is not available. Add a function to read it.

Note that all functions sill use the BSS version of the data.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
Tested-by: Bin Meng <bmeng.cn@gmail.com>

include/cbfs.h

@@ -90,6 +90,13 @@ extern enum cbfs_result file_cbfs_result;
  */
 const char *file_cbfs_error(void);
 
+/**
+ * cbfs_get_result() - Get the result of the last CBFS operation
+ *
+ *@return last result
+ */
+enum cbfs_result cbfs_get_result(void);
+
 /**
  * file_cbfs_init() - Initialize the CBFS driver and load metadata into RAM.
  *