arm64: KVM: use 'int' instead of 'u32' for variable 'target' in kvm_host.h.

arm64: KVM: use 'int' instead of 'u32' for variable 'target' in kvm_host.h.

'target' will be set to '-1' in kvm_arch_vcpu_init(), and it need check
'target' whether less than zero or not in kvm_vcpu_initialized().

So need define target as 'int' instead of 'u32', just like ARM has done.

The related warning:

  arch/arm64/kvm/../../../arch/arm/kvm/arm.c:497:2: warning: comparison of unsigned expression >= 0 is always true [-Wtype-limits]

Signed-off-by: Chen Gang <gang.chen@asianux.com>
[Marc: reformated the Subject line to fit the series]
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
(cherry picked from commit 6c8c0c4dc0e98ee2191211d66e9f876e95787073)
Signed-off-by: Christoffer Dall <christoffer.dall@linaro.org>