kvm: use DIV_ROUND_UP

I used the clang-tidy qemu-round check to generate the fix:
https://github.com/elmarco/clang-tools-extraSigned-off-by: NMarc-André Lureau <marcandre.lureau@redhat.com>
Reviewed-by: NRichard Henderson <rth@twiddle.net>

linux-headers/asm-x86/kvm.h

@@ -153,7 +153,7 @@ struct kvm_sregs {
 	__u64 cr0, cr2, cr3, cr4, cr8;
 	__u64 efer;
 	__u64 apic_base;
-	__u64 interrupt_bitmap[(KVM_NR_INTERRUPTS + 63) / 64];
+	__u64 interrupt_bitmap[DIV_ROUND_UP(KVM_NR_INTERRUPTS, 64)];
 };
 
 /* for KVM_GET_FPU and KVM_SET_FPU */