EDAC/amd64: Recognize DRAM device type ECC capability

AMD Family 17h systems support x4 and x16 DRAM devices. However, the
device type is not checked when setting mci.edac_ctl_cap.

Set the appropriate capability flag based on the device type.

Default to x8 DRAM device when neither the x4 or x16 bits are set.

 [ bp: reverse cpk_en check to save an indentation level. ]

Fixes: 2d09d8f3 ("EDAC, amd64: Determine EDAC MC capabilities on Fam17h")
Signed-off-by: Yazen Ghannam <yazen.ghannam@amd.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Cc: "linux-edac@vger.kernel.org" <linux-edac@vger.kernel.org>
Cc: James Morse <james.morse@arm.com>
Cc: Mauro Carvalho Chehab <mchehab@kernel.org>
Cc: Tony Luck <tony.luck@intel.com>
Link: https://lkml.kernel.org/r/20190821235938.118710-3-Yazen.Ghannam@amd.com