firmware: imx: add COMPILE_TEST support

Add COMPILE_TEST support to i.MX SCU drivers for better compile
testing coverage.

Signed-off-by: Anson Huang <Anson.Huang@nxp.com>
Link: https://lore.kernel.org/r/1583509356-8265-1-git-send-email-Anson.Huang@nxp.com


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>