EDAC/amd64: Correct number of UMCs for family 19h models 70h-7fh

AMD's Family 19h-based Models 70h-7fh support 4 unified memory controllers
(UMC) per processor die.

The amd64_edac driver, however, assumes only 2 UMCs are supported since
max_mcs variable for the models has not been explicitly set to 4. The same
results in incomplete or incorrect memory information being logged to dmesg by
the module during initialization in some instances.

Fixes: 6c79e42 ("EDAC/amd64: Add support for ECC on family 19h model 60h-7Fh")
Closes: https://lore.kernel.org/all/27dc093f-ce27-4c71-9e81-786150a040b6@reox.at/
Reported-by: reox <mailinglist@reox.at>
Signed-off-by: Avadhut Naik <avadhut.naik@amd.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Cc: stable@kernel.org
Link: https://lore.kernel.org/20250613005233.2330627-1-avadhut.naik@amd.com

Author: Avadhut Naik

drivers/edac/amd64_edac.c

@@ -3879,6 +3879,7 @@ static int per_family_init(struct amd64_pvt *pvt)
 			break;
 		case 0x70 ... 0x7f:
 			pvt->ctl_name			= "F19h_M70h";
+			pvt->max_mcs			= 4;
 			pvt->flags.zn_regs_v2		= 1;
 			break;
 		case 0x90 ... 0x9f: