drm/i915/kbl: s/KBL/KABYLAKE for platform/subplatform defines

drm/i915/kbl: s/KBL/KABYLAKE for platform/subplatform defines

Follow consistent naming convention. Replace KBL with
KABYLAKE.Replace IS_KBL_GRAPHICS_STEP with
IS_KABYLAKE () && IS_GRAPHICS_STEP().

v2:
- s/KBL/kbl in the subject prefix(Anusha)

v3:
- Unrolled wrapper IS_KBL_GRAPHICS_STEP.
- Replace with IS_PLATFORM && DISPLAY_STEP(tvrtko/jani)

v4:
- Removed unused macro.

Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Cc: Jani Nikula <jani.nikula@linux.intel.com>
Cc: Anusha Srivatsa <Anusha.Srivatsa@intel.com>
Signed-off-by: Dnyaneshwar Bhadane <dnyaneshwar.bhadane@intel.com>
Reviewed-by: Anusha Srivatsa <anusha.srivatsa@intel.com>
Acked-by: Jani Nikula <jani.nikula@intel.com>
Signed-off-by: Radhakrishna Sripada <radhakrishna.sripada@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230801135344.3797924-5-dnyaneshwar.bhadane@intel.com