KVM: selftests: Rename x86's vcpu_setup() to vcpu_init_sregs()

Rename vcpu_setup() to be more descriptive and precise, there is a whole
lot of "setup" that is done for a vCPU that isn't in said helper.

No functional change intended.
Reviewed-by: Ackerley Tng <ackerleytng@google.com>
Link: https://lore.kernel.org/r/20240314232637.2538648-10-seanjc@google.comSigned-off-by: Sean Christopherson <seanjc@google.com>

tools/testing/selftests/kvm/lib/x86_64/processor.c

@@ -556,7 +556,7 @@ void vcpu_init_descriptor_tables(struct kvm_vcpu *vcpu)
 	*(vm_vaddr_t *)addr_gva2hva(vm, (vm_vaddr_t)(&exception_handlers)) = vm->handlers;
 }
 
-static void vcpu_setup(struct kvm_vm *vm, struct kvm_vcpu *vcpu)
+static void vcpu_init_sregs(struct kvm_vm *vm, struct kvm_vcpu *vcpu)
 {
 	struct kvm_sregs sregs;
 
@@ -719,7 +719,7 @@ struct kvm_vcpu *vm_arch_vcpu_add(struct kvm_vm *vm, uint32_t vcpu_id)
 
 	vcpu = __vm_vcpu_add(vm, vcpu_id);
 	vcpu_init_cpuid(vcpu, kvm_get_supported_cpuid());
-	vcpu_setup(vm, vcpu);
+	vcpu_init_sregs(vm, vcpu);
 
 	/* Setup guest general purpose registers */
 	vcpu_regs_get(vcpu, &regs);