KVM: x86: Rename find_highest_vector()

In preparation for moving kvm-internal find_highest_vector() to
apic.h for use in Secure AVIC APIC driver, rename find_highest_vector()
to apic_find_highest_vector() as part of the APIC API.

No functional change intended.

Signed-off-by: Neeraj Upadhyay <Neeraj.Upadhyay@amd.com>
Acked-by: Sean Christopherson <seanjc@google.com>
Link: https://lore.kernel.org/r/20250709033242.267892-7-Neeraj.Upadhyay@amd.com
Signed-off-by: Sean Christopherson <seanjc@google.com>

Author: neerajupadhya

arch/x86/kvm/lapic.c

@@ -616,7 +616,7 @@ static const unsigned int apic_lvt_mask[KVM_APIC_MAX_NR_LVT_ENTRIES] = {
 	[LVT_CMCI] = LVT_MASK | APIC_MODE_MASK
 };
 
-static int find_highest_vector(void *bitmap)
+static int apic_find_highest_vector(void *bitmap)
 {
 	int vec;
 	u32 *reg;
@@ -695,7 +695,7 @@ EXPORT_SYMBOL_GPL(kvm_apic_update_irr);
 
 static inline int apic_search_irr(struct kvm_lapic *apic)
 {
-	return find_highest_vector(apic->regs + APIC_IRR);
+	return apic_find_highest_vector(apic->regs + APIC_IRR);
 }
 
 static inline int apic_find_highest_irr(struct kvm_lapic *apic)
@@ -776,7 +776,7 @@ static inline int apic_find_highest_isr(struct kvm_lapic *apic)
 	if (likely(apic->highest_isr_cache != -1))
 		return apic->highest_isr_cache;
 
-	result = find_highest_vector(apic->regs + APIC_ISR);
+	result = apic_find_highest_vector(apic->regs + APIC_ISR);
 	ASSERT(result == -1 || result >= 16);
 
 	return result;