valgrind/i386: avoid false positives on KVM_GET_MSRS ioctl

struct kvm_msrs contains a pad field. Let's use a designated
initializer on the info part to avoid false positives from
valgrind/memcheck.

Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
