nvmem: octop: Add i.MX7D support

Add i.MX7D support.
There is 16 banks, each bank 4 words.

Signed-off-by: Peng Fan <peng.fan@nxp.com>
Cc: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
Cc: Maxime Ripard <maxime.ripard@free-electrons.com>
Cc: Shawn Guo <shawnguo@kernel.org>
Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>