KVM: Portability: Move kvm_fpu to asm-x86/kvm.h

This patch moves kvm_fpu asm-x86/kvm.h to allow every architecture to
define an own representation used for KVM_GET_FPU/KVM_SET_FPU.

Signed-off-by: Christian Ehrhardt <ehrhardt@linux.vnet.ibm.com>
Acked-by: Carsten Otte <cotte@de.ibm.com>
Acked-by: Zhang Xiantao <xiantao.zhang@intel.com>
Signed-off-by: Avi Kivity <avi@qumranet.com>