regulator: rtmv20: Fix to make regcache value first reading back from HW

stable inclusion
from stable-5.10.46
commit 0ea21221dd5a914205f206835e0d43f8ca23d494
bugzilla: 168323
CVE: NA

--------------------------------

[ Upstream commit 46639a5e ]

- Fix to make regcache value first reading back from HW.

Signed-off-by: ChiYuan Huang <cy_huang@richtek.com>
Link: https://lore.kernel.org/r/1622542155-6373-1-git-send-email-u0084500@gmail.com


Signed-off-by: Mark Brown <broonie@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Chen Jun <chenjun102@huawei.com>
Acked-by: Weilong Chen <chenweilong@huawei.com>
Signed-off-by: Zheng Zengkai <zhengzengkai@huawei.com>