EDAC/amd64: Recognize x16 symbol size

Future AMD systems may support x16 symbol sizes.

Recognize if a system is using x16 symbol size. Also, simplify the print
statement.

Note that a x16 syndrome vector table is not necessary like with x4 or
x8 syndromes. This is because systems that support x16 symbol sizes are
SMCA systems and in that case, the syndrome can be directly extracted
from the MCA_SYND[Syndrome] field.

 [ bp: massage. ]

Signed-off-by: Yazen Ghannam <yazen.ghannam@amd.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Tested-by: Kim Phillips <kim.phillips@amd.com>
Cc: James Morse <james.morse@arm.com>
Cc: Mauro Carvalho Chehab <mchehab@kernel.org>
Cc: linux-edac <linux-edac@vger.kernel.org>
Link: https://lkml.kernel.org/r/20190228153558.127292-4-Yazen.Ghannam@amd.com

drivers/edac/amd64_edac.h

@@ -364,7 +364,7 @@ struct amd64_pvt {
 	u32 dct_sel_hi;		/* DRAM Controller Select High */
 	u32 online_spare;	/* On-Line spare Reg */
 
-	/* x4 or x8 syndromes in use */
+	/* x4, x8, or x16 syndromes in use */
 	u8 ecc_sym_sz;
 
 	/* place to store error injection parameters prior to issue */