KVM: arm64: Fix inject_fault.c kernel-doc warnings

Fix kernel-doc warnings.
arch/arm64/kvm/inject_fault.c:210: warning: Function parameter or member
'vcpu' not described in 'kvm_inject_undefined'

Signed-off-by: Tian Tao <tiantao6@hisilicon.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Acked-by: Will Deacon <will@kernel.org>
Link: https://lore.kernel.org/r/1600154512-44624-1-git-send-email-tiantao6@hisilicon.com