KVM: x86: Add missing inline tag to kvm_read_and_reset_pf_reason

May otherwise generates build warnings about unused
kvm_read_and_reset_pf_reason if included without CONFIG_KVM_GUEST
enabled.

Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>

arch/x86/include/asm/kvm_para.h

@@ -182,7 +182,7 @@ u32 kvm_read_and_reset_pf_reason(void);
 #define kvm_guest_init() do { } while (0)
 #define kvm_async_pf_task_wait(T) do {} while(0)
 #define kvm_async_pf_task_wake(T) do {} while(0)
-static u32 kvm_read_and_reset_pf_reason(void)
+static inline u32 kvm_read_and_reset_pf_reason(void)
 {
 	return 0;
 }