drm/i915/display: Include debugfs.h in intel_display_debugfs_params.c

Commit 8015bee0bfec ("drm/i915/display: Add framework to add parameters
specific to display") added the file intel_display_debugfs_params.c,
which calls the functions "debugfs_create_{bool, ulong, str}" -- all of
which are defined in <linux/debugfs.h>. The missing inclusion of this
header file is breaking the ChromeOS build -- add an explicit include
to fix that.

Signed-off-by: Paz Zcharya <pazz@chromium.org>
Reviewed-by: Jani Nikula <jani.nikula@intel.com>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240131204658.795278-1-pazz@chromium.org

drm/i915/display: Add framework to add parameters specific to display

Currently all module parameters are handled by i915_param.c/h. This
is a problem for display parameters when Xe driver is used. Add
a mechanism to add parameters specific to the display. This is mainly
copied from i915_[debugfs]_params.[ch]. Parameters are not yet moved. This
is done by subsequent patches.

v2:
- Drop unused predefinition (dentry)
- Clarify need for empty INTEL_DISPLAY_PARAMS_FOR_EACH in comment

Signed-off-by: Jouni Högander <jouni.hogander@intel.com>
Acked-by: Jani Nikula <jani.nikula@intel.com>
Reviewed-by: Luca Coelho <luciano.coelho@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20231024124109.384973-2-jouni.hogander@intel.com