KVM: selftests: Add a missing apostrophe in comment to show ownership

Add an apostrophe in a comment about it being the caller's, not callers,
responsibility to free an object.

Reported-by: Andrew Jones <drjones@redhat.com>
Fixes: 768e9a6185 ("KVM: selftests: Purge vm+vcpu_id == vcpu silliness")
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20220613161942.1586791-2-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

tools/testing/selftests/kvm/lib/kvm_util.c

@@ -1434,7 +1434,7 @@ void vcpu_run_complete_io(struct kvm_vcpu *vcpu)
 /*
  * Get the list of guest registers which are supported for
  * KVM_GET_ONE_REG/KVM_SET_ONE_REG ioctls.  Returns a kvm_reg_list pointer,
- * it is the callers responsibility to free the list.
+ * it is the caller's responsibility to free the list.
  */
 struct kvm_reg_list *vcpu_get_reg_list(struct kvm_vcpu *vcpu)
 {