It must read the entire image for previous code of 'imsz' or 'imszb'. Signed-off-by: Jianhui Zhao <zhaojh329@gmail.com> Suggested-by: Chuanhong Guo <gch981213@gmail.com> (cherry picked from commit 3bbc1d5fba1d700917138334a48c16bafdf48de9)