Use "FIELD_GET()" and "FIELD_PREP()" to simplify the code.

[dlezcano] : Changed title
Signed-off-by: 周琰杰 (Zhou Yanjie) <zhouyanjie@wanyeetech.com>
Reviewed-by: Paul Cercueil <paul@crapouillou.net>
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Link: https://lore.kernel.org/r/1627638188-116163-1-git-send-email-zhouyanjie@wanyeetech.com