nvmem: rockchip-otp: Add support for RK3528

Add support for the OTP controller in RK3528. The OTPC is similar to the
OTPC in RK3562 and RK3568, exept for a missing phy clock and reset.

Signed-off-by: Jonas Karlman <jonas@kwiboo.se>
Signed-off-by: Heiko Stuebner <heiko@sntech.de>
Tested-by: Willy Tarreau <w@1wt.eu>
Signed-off-by: Srinivas Kandagatla <srini@kernel.org>