target/i386/hvf: add rdmsr 35H MSR_CORE_THREAD_COUNT

target/i386/hvf: add rdmsr 35H MSR_CORE_THREAD_COUNT

Some guests (ex. Darwin-XNU) can attemp to read this MSR to retrieve and
validate CPU topology comparing it to ACPI MADT content

MSR description from Intel Manual:
35H: MSR_CORE_THREAD_COUNT: Configured State of Enabled Processor Core
  Count and Logical Processor Count

Bits 15:0 THREAD_COUNT The number of logical processors that are
  currently enabled in the physical package

Bits 31:16 Core_COUNT The number of processor cores that are currently
  enabled in the physical package

Bits 63:32 Reserved

Signed-off-by: Vladislav Yaroshchuk <yaroshchuk2000@gmail.com>
Message-Id: <20210113205323.33310-1-yaroshchuk2000@gmail.com>
[RB: reordered MSR definition and dropped u suffix from shift offset]
Signed-off-by: Roman Bolshakov <r.bolshakov@yadro.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>