x86/mtrr: Don't print errors if MtrrFixDramModEn is set when SNP enabled

x86/mtrr: Don't print errors if MtrrFixDramModEn is set when SNP enabled

SNP enabled platforms require the MtrrFixDramModeEn bit to be set across
all CPUs when SNP is enabled. Therefore, don't print error messages when
MtrrFixDramModeEn is set when bringing CPUs online.

Closes: https://lore.kernel.org/kvm/68b2d6bf-bce7-47f9-bebb-2652cc923ff9@linux.microsoft.com/
Reported-by: Jeremi Piotrowski <jpiotrowski@linux.microsoft.com>
Signed-off-by: Ashish Kalra <ashish.kalra@amd.com>
Signed-off-by: Michael Roth <michael.roth@amd.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Link: https://lore.kernel.org/r/20240126041126.1927228-6-michael.roth@amd.com