The compatible DDR controllers may support DDR, DDR2, DDR3, DDR4 DRAM.
An individual controller doesn't support all of them. The EDAC driver
reads SDRAM_CFG to determine which mode is configured.

Add DDR4 and drop the defines used only in the mtype assignment.
Signed-off-by: York Sun <york.sun@nxp.com>
Cc: linux-edac <linux-edac@vger.kernel.org>
Cc: morbidrsa@gmail.com
Cc: oss@buserror.net
Cc: stuart.yoder@nxp.com
Link: http://lkml.kernel.org/r/1470779760-16483-6-git-send-email-york.sun@nxp.comSigned-off-by: Borislav Petkov <bp@suse.de>