KVM: Trivial: Use standard BITMAP macros, open-code userspace-exposed header

Creating one's own BITMAP macro seems suboptimal: if we use manual
arithmetic in the one place exposed to userspace, we can use standard
macros elsewhere.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Avi Kivity <avi@qumranet.com>
diff --git a/drivers/kvm/kvm_main.c b/drivers/kvm/kvm_main.c
index af02320..fc63de2 100644
--- a/drivers/kvm/kvm_main.c
+++ b/drivers/kvm/kvm_main.c
@@ -2130,7 +2130,7 @@
 	memcpy(vcpu->irq_pending, sregs->interrupt_bitmap,
 	       sizeof vcpu->irq_pending);
 	vcpu->irq_summary = 0;
-	for (i = 0; i < NR_IRQ_WORDS; ++i)
+	for (i = 0; i < ARRAY_SIZE(vcpu->irq_pending); ++i)
 		if (vcpu->irq_pending[i])
 			__set_bit(i, &vcpu->irq_summary);