nvmem: imx-ocotp: Update module description

This imx-ocotp driver encapsulates support for a subset of both i.MX6 and
i.MX7 processors. Update the module description to reflect.

Fixes: 711d4547 ("nvmem: octop: Add i.MX7D support")

Signed-off-by: Bryan O'Donoghue <pure.logic@nexus-software.ie>
Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>