forked from Mirrors/opensbi

Because *out needs to reserve a byte to hold '\0', no more characters should be added to the buffer when *out has one byte left, and the buffer size *out_len should not be modified. this patch prevents the correction of *out_len when *out_len is 1. Signed-off-by: Xiang W <wxjstz@126.com> Reviewed-by: Anup Patel <anup@brainfault.org>