sign-file: Support SM signature

euleros inclusion
category: feature
bugzilla: https://gitee.com/openeuler/kernel/issues/I5ETJZ


CVE: NA

--------

openeuler openssl now supports SM certificate. The type of key should
be set to EVP_PKEY_SM2 before using.

Signed-off-by: luhuaxin <luhuaxin1@huawei.com>
Reviewed-by: Xiu Jianfeng <xiujianfeng@huawei.com>
Signed-off-by: Zheng Zengkai <zhengzengkai@huawei.com>