drm/xe/kunit: Handle fake device creation for all platform/subplatform cases

drm/xe/kunit: Handle fake device creation for all platform/subplatform cases

For platform like Alderlake P there are subplatforms and
just Alderlake P. Unlike DG2 in which every flavour is
either a G10,G11 or G12 variant. In this case(Alderlake P/S),
the Kunit test evaluates the subplatform to NONE and is
unable to create a fake device. Removing the condition
in xe_pci_fake_device_init() to support this corner case
so driver can proceed with the unit testing.

Cc: Lucas De Marchi <lucas.demarchi@intel.com>
Signed-off-by: Anusha Srivatsa <anusha.srivatsa@intel.com>
Reviewed-by: Lucas De Marchi <lucas.demarchi@intel.com>
Link: https://lore.kernel.org/r/20230613174740.786041-1-anusha.srivatsa@intel.com
Signed-off-by: Lucas De Marchi <lucas.demarchi@intel.com>
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>