intel: Export total subslice and EU counts

Update kernel interface with new I915_GETPARAM ioctl entries for
subslice total and EU total. Add a wrapping function for each
parameter. Userspace drivers need these values when constructing
GPGPU commands. This kernel query method is intended to replace
the PCI ID-based tables that userspace drivers currently maintain.
The kernel driver can employ fuse register reads as needed to
ensure the most accurate determination of GT config attributes.
This first became important with Cherryview in which the config
could differ between devices with the same PCI ID.

The kernel detection of these values is device-specific. Userspace
drivers should continue to maintain ID-based tables for older
devices which return ENODEV when using this query.

v2: remove unnecessary include of <stdbool.h> and increment the
    I915_GETPARAM indices to match updated kernel patch.

For: VIZ-4636
Reviewed-by: Damien Lespiau <damien.lespiau@intel.com>
Signed-off-by: Jeff McGee <jeff.mcgee@intel.com>
Signed-off-by: Damien Lespiau <damien.lespiau@intel.com>