KVM: X86: init irq->level in kvm_pv_kick_cpu_op

'lapic_irq' is a local variable and its 'level' field isn't
initialized, so 'level' is random, it doesn't matter but
makes UBSAN unhappy:

UBSAN: Undefined behaviour in .../lapic.c:...
load of value 10 is not a valid value for type '_Bool'
...
Call Trace:
 [<ffffffff81f030b6>] dump_stack+0x1e/0x20
 [<ffffffff81f03173>] ubsan_epilogue+0x12/0x55
 [<ffffffff81f03b96>] __ubsan_handle_load_invalid_value+0x118/0x162
 [<ffffffffa1575173>] kvm_apic_set_irq+0xc3/0xf0 [kvm]
 [<ffffffffa1575b20>] kvm_irq_delivery_to_apic_fast+0x450/0x910 [kvm]
 [<ffffffffa15858ea>] kvm_irq_delivery_to_apic+0xfa/0x7a0 [kvm]
 [<ffffffffa1517f4e>] kvm_emulate_hypercall+0x62e/0x760 [kvm]
 [<ffffffffa113141a>] handle_vmcall+0x1a/0x30 [kvm_intel]
 [<ffffffffa114e592>] vmx_handle_exit+0x7a2/0x1fa0 [kvm_intel]
...

Signed-off-by: Longpeng(Mike) <longpeng2@huawei.com>
Signed-off-by: Radim Krčmář <rkrcmar@redhat.com>