hvm svm: Fix for BSOD when "migrating" from Intel to AMD.

hvm svm: Fix for BSOD when "migrating" from Intel to AMD.

The Intel processor driver for Windows (XP and later at least) reads
an MSR that AMD doesn't have. This causes GP-fault in kernel mode,
which causes blue-screen-of-death on Windows. This prevents a
disk-image that was installed on Intel from starting on an AMD
processor.

This patch "fixes" the problem by allowing reads from the msr,
returning all zero's (which is a valid, if not particulary
meaningful, value for this register).

Signed-off-by: Mats Petersson <mats.petersson@amd.com>