nvmem: imx-ocotp: add COMPILE_TEST for proper test coverage

This patch add COMPILE_TEST to imx-ocotp driver so that it can be
compile tested on other platforms with zero day testing.
Also adds HAS_IOMEM dependancy as the users of devm_ioremap_resource()
which are compile-testable should depend on HAS_IOMEM.

Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
Acked-by: Philipp Zabel <p.zabel@pengutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>