KVM: ia64: fix build breakage due to host spinlock change

Len Brown pointed out that allmodconfig is broken for
ia64 because of:

arch/ia64/kvm/vmm.c: In function 'vmm_spin_unlock':
arch/ia64/kvm/vmm.c:70: error: 'spinlock_t' has no member named 'raw_lock'

KVM has it's own spinlock routines. It should not depend on the base kernel
spinlock_t type (which changed when ia64 switched to ticket locks).  Define
its own vmm_spinlock_t type.

Signed-off-by: Tony Luck <tony.luck@intel.com>
Signed-off-by: Avi Kivity <avi@redhat.com>