kvm: Delete prototype for non-existent function kvm_check_iopl

The prototype for kvm_check_iopl appeared in commit
f850e2e6 ("KVM: x86 emulator: Check IOPL
level during io instruction emulation"), but the function never actually
existed.  Remove the prototype.
Signed-off-by: Josh Triplett <josh@joshtriplett.org>
Signed-off-by: Gleb Natapov <gleb@redhat.com>

arch/x86/include/asm/kvm_host.h

@@ -936,8 +936,6 @@ void kvm_mmu_new_cr3(struct kvm_vcpu *vcpu);
 void kvm_enable_tdp(void);
 void kvm_disable_tdp(void);
 
-bool kvm_check_iopl(struct kvm_vcpu *vcpu);
-
 static inline gpa_t translate_gpa(struct kvm_vcpu *vcpu, gpa_t gpa, u32 access)
 {
 	return gpa;