KVM: x86: change vcpu->arch.switch_db_regs to a bit mask

The next patch will add another bit that we can test with the
same "if".

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

arch/x86/include/asm/kvm_host.h

@@ -337,6 +337,10 @@ struct kvm_pmu {
 	u64 reprogram_pmi;
 };
 
+enum {
+	KVM_DEBUGREG_BP_ENABLED = 1,
+};
+
 struct kvm_vcpu_arch {
 	/*
 	 * rip and regs accesses must go through
@@ -463,7 +467,7 @@ struct kvm_vcpu_arch {
 	struct mtrr_state_type mtrr_state;
 	u32 pat;
 
-	int switch_db_regs;
+	unsigned switch_db_regs;
 	unsigned long db[KVM_NR_DB_REGS];
 	unsigned long dr6;
 	unsigned long dr7;