KVM: x86: Change return type of is_long_mode() to bool

Change return type of is_long_mode() to bool to avoid implicit cast,
as literally every user of is_long_mode() treats its return value as a
boolean.
Signed-off-by: Binbin Wu <binbin.wu@linux.intel.com>
Link: https://lore.kernel.org/r/20230322045824.22970-5-binbin.wu@linux.intel.comReviewed-by: Kai Huang <kai.huang@intel.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>

arch/x86/kvm/x86.h

@@ -126,12 +126,12 @@ static inline bool is_protmode(struct kvm_vcpu *vcpu)
 	return kvm_is_cr0_bit_set(vcpu, X86_CR0_PE);
 }
 
-static inline int is_long_mode(struct kvm_vcpu *vcpu)
+static inline bool is_long_mode(struct kvm_vcpu *vcpu)
 {
 #ifdef CONFIG_X86_64
-	return vcpu->arch.efer & EFER_LMA;
+	return !!(vcpu->arch.efer & EFER_LMA);
 #else
-	return 0;
+	return false;
 #endif
 }