rockchip: otp: Refactor to use driver data and ops

Refactor the driver to use driver data and ops to simplify handling
of SoCs that require a unique read op.

Use readl_poll_sleep_timeout instead of a custom poll loop, and add
validation of input parameter to main read op.

Signed-off-by: Jonas Karlman <jonas@kwiboo.se>
Reviewed-by: Kever Yang <kever.yang@rock-chips.com>