docs: vfio: fix header path

The text points to a different header file, fix by changing
the path to "uapi".
Signed-off-by: Jiri Pirko <jiri@nvidia.com>
Reviewed-by: Yi Liu <yi.l.liu@intel.com>
Link: https://lore.kernel.org/r/20230310095857.985814-1-jiri@resnulli.usSigned-off-by: Jonathan Corbet <corbet@lwn.net>

Documentation/driver-api/vfio.rst

@@ -242,7 +242,7 @@ group and can access them as follows::
 VFIO User API
 -------------------------------------------------------------------------------
 
-Please see include/linux/vfio.h for complete API documentation.
+Please see include/uapi/linux/vfio.h for complete API documentation.
 
 VFIO bus driver API
 -------------------------------------------------------------------------------