drm/i915: Remove unnecessary include

The inclusion of intel_gt_defines.h was initially added to
i915_drv.h to provide the definition of I915_MAX_GT, where it was
originally defined.

However, since I915_MAX_GT is now included in
i915_gem_object_types.h, it sis no longer required in i915_drv.h.

Signed-off-by: Andi Shyti <andi.shyti@linux.intel.com>
Cc: Chris Wilson <chris.p.wilson@linux.intel.com>
Reviewed-by: Mauro Carvalho Chehab <mchehab@kernel.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20230801141955.383305-5-andi.shyti@linux.intel.com