hwrng: Add support for Phytium SoC RNG

phytium inclusion
category: feature
bugzilla: https://gitee.com/openeuler/kernel/issues/I8A24Y


CVE: NA

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This driver provides kernel-side support for the Random Number Generator
 hardware found on Phytium SoCs.

Signed-off-by: Zhang Yiqun <zhangyiqun@phytium.com.cn>
Signed-off-by: Chen Baozi <chenbaozi@phytium.com.cn>
Signed-off-by: Xu Yan <xuyan1481@phytium.com.cn>