The command 'flash erase_check' showed the message 'Running slow fallback erase check - add working memory' even in the case the target didn't implement blank_check_memory. Change return code of target_blank_check_memory() in this case and sense it in default_flash_blank_check() and show a message without a request for working memory. Change-Id: I7cf9bf77742964b4f377c9ce48ca689e57d0882f Signed-off-by: Tomas Vanek <vanekt@fbl.cz> Reviewed-on: https://review.openocd.org/c/openocd/+/6765 Tested-by: jenkins Reviewed-by: Tim Newsome <tim@sifive.com>