KVM: SVM: Fix benign "bool vs. int" comparison in svm_set_cr0()

Explicitly convert the return from is_paging() to a bool when comparing
against old_paging, which is also a boolean.  is_paging() sneakily uses
kvm_read_cr0_bits() and returns an int, i.e. returns X86_CR0_PG or 0, not
1 or 0.

Luckily, the bug is benign as it only results in a false positive, not a
false negative, i.e. only causes a spurious refresh of CR4 when paging is
enabled in both the old and new.

Cc: Maxim Levitsky <mlevitsk@redhat.com>
Fixes: c53bbe21 ("KVM: x86: SVM: don't passthrough SMAP/SMEP/PKE bits in !NPT && !gCR0.PG case")
Signed-off-by: Sean Christopherson <seanjc@google.com>

arch/x86/kvm/svm/svm.c

@@ -1802,7 +1802,7 @@ void svm_set_cr0(struct kvm_vcpu *vcpu, unsigned long cr0)
 
 	if (!npt_enabled) {
 		hcr0 |= X86_CR0_PG | X86_CR0_WP;
-		if (old_paging != is_paging(vcpu))
+		if (old_paging != !!is_paging(vcpu))
 			svm_set_cr4(vcpu, kvm_read_cr4(vcpu));
 	}