imx8qxp_mek: Disable CONFIG_DISPLAY_CPUINFO

Due to revert of commit c0434407, this board does not build
any more. Disable CONFIG_DISPLAY_CPUINFO for v2018.11 release.

This commit should be reverted after v2018.11 release.

Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
Acked-by: Peng Fan <peng.fan@nxp.com>
Reviewed-by: Simon Glass <sjg@chromium.org>