drm/i915/utils: drop unnecessary ifdefs

drm/i915/utils: drop unnecessary ifdefs

The i915_utils.h and intel_display_utils.h were in some cases included
from the same files, the former via i915_drv.h and the latter
directly. This lead to a clash between MISSING_CASE() and
fetch_and_zero() defined in both, requiring ifdefs.

With the display dependency on i915_drv.h removed, we can also remove
the now unnecessary ifdefs.

Reviewed-by: Matt Roper <matthew.d.roper@intel.com>
Link: https://patch.msgid.link/f40a1fd365cbcfb77bd76ce0041c4523699f6052.1767009044.git.jani.nikula@intel.com
Signed-off-by: Jani Nikula <jani.nikula@intel.com>