vfio-pci: Fix vfio_pci_ioeventfd() to return int

This only returns 0 or -ERRNO, it should return int like all the other
ioctl dispatch functions.
Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
Link: https://lore.kernel.org/r/1-v2-0f9e632d54fb+d6-vfio_ioctl_split_jgg@nvidia.comSigned-off-by: Alex Williamson <alex.williamson@redhat.com>

drivers/vfio/pci/vfio_pci_priv.h

@@ -48,7 +48,7 @@ static inline ssize_t vfio_pci_vga_rw(struct vfio_pci_core_device *vdev,
 }
 #endif
 
-long vfio_pci_ioeventfd(struct vfio_pci_core_device *vdev, loff_t offset,
+int vfio_pci_ioeventfd(struct vfio_pci_core_device *vdev, loff_t offset,
 		       uint64_t data, int count, int fd);
 
 int vfio_pci_init_perm_bits(void);

drivers/vfio/pci/vfio_pci_rdwr.c

@@ -412,7 +412,7 @@ static void vfio_pci_ioeventfd_thread(void *opaque, void *unused)
 	vfio_pci_ioeventfd_do_write(ioeventfd, ioeventfd->test_mem);
 }
 
-long vfio_pci_ioeventfd(struct vfio_pci_core_device *vdev, loff_t offset,
+int vfio_pci_ioeventfd(struct vfio_pci_core_device *vdev, loff_t offset,
 		       uint64_t data, int count, int fd)
 {
 	struct pci_dev *pdev = vdev->pdev;