drm/xe/xe2: Determine bios enablement for flat ccs on igfx

If bios disables flat ccs on igfx make has_flat_ccs as 0 and notify
via drm_dbg.

Bspec:59255

v2:
 - Release forcewake.
 - Add registers in order.
 - drop dgfx condition and only add it back in the future
when the support for an Xe2 dgpu will be added.
- Use drm_dbg instead of drm_info. (Matt)

v3:
 - Address nit(Matt)

Cc: Matt Roper <matthew.d.roper@intel.com>
Cc: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Signed-off-by: Himal Prasad Ghimiray <himal.prasad.ghimiray@intel.com>
Reviewed-by: Matt Roper <matthew.d.roper@intel.com>
Acked-by: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>