misc: add driver for the Rockchip otp controller

Newer Rockchip socs like the px30 use a different ip block to handle
one-time-programmable memory, so add a misc driver for it as well.

Signed-off-by: Finley Xiao <finley.xiao@rock-chips.com>
Signed-off-by: Heiko Stuebner <heiko.stuebner@theobroma-systems.com>
Reviewed-by: Kever Yang <kever.yang@rock-chips.com>