KVM: MIPS: Remove a "set but not used" variable

This fix a build warning:

   arch/mips/kvm/vz.c: In function '_kvm_vz_restore_htimer':
>> arch/mips/kvm/vz.c:392:10: warning: variable 'freeze_time' set but not used [-Wunused-but-set-variable]
     392 |  ktime_t freeze_time;
         |          ^~~~~~~~~~~
Reported-by: Nkernel test robot <lkp@intel.com>
Signed-off-by: NHuacai Chen <chenhuacai@loongson.cn>
Message-Id: <20210406024911.2008046-1-chenhuacai@loongson.cn>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

arch/mips/kvm/vz.c

@@ -388,7 +388,6 @@ static void _kvm_vz_restore_htimer(struct kvm_vcpu *vcpu,
 				   u32 compare, u32 cause)
 {
 	u32 start_count, after_count;
-	ktime_t freeze_time;
 	unsigned long flags;
 
 	/*
@@ -396,7 +395,7 @@ static void _kvm_vz_restore_htimer(struct kvm_vcpu *vcpu,
 	 * this with interrupts disabled to avoid latency.
 	 */
 	local_irq_save(flags);
-	freeze_time = kvm_mips_freeze_hrtimer(vcpu, &start_count);
+	kvm_mips_freeze_hrtimer(vcpu, &start_count);
 	write_c0_gtoffset(start_count - read_c0_count());
 	local_irq_restore(flags);