nvmem: imx-ocotp: Implement i.MX6ULL/ULZ support

In comparision to the i.MX6UL the lower cost variants i.MX6ULL/ULZ only
supports 8 OTP banks a 8 words.

Signed-off-by: Stefan Wahren <stefan.wahren@i2se.com>
Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>