drm/i915/gt: Drop invalidate_csb_entries

Drop invalidate_csb_entries and directly call drm_clflush_virt_range.
This allows for one less function call, and prevent complier errors when
building for non-x86 architectures.

v2(Michael Cheng): Drop invalidate_csb_entries function and directly
		   invoke drm_clflush_virt_range. Thanks to Tvrtko for the
		   sugguestion.

v3(Michael Cheng): Use correct parameters for drm_clflush_virt_range.
		   Thanks to Tvrtko for pointing this out.

v4(Michael Cheng): Simplify &execlists->csb_status[0] to
		   execlists->csb_status. Thanks to Matt Roper for the
		   suggestion.

Signed-off-by: Michael Cheng <michael.cheng@intel.com>
Reviewed-by: Matt Roper <matthew.d.roper@intel.com>
Signed-off-by: Matt Roper <matthew.d.roper@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220321223819.72833-3-michael.cheng@intel.com