drm/i915/audio: convert to struct intel_display
Going forward, struct intel_display will be the main display device
structure. Convert intel_audio.[ch] to it, as much as possible
anyway. Do some minor checkpatch fixes while at it.
Reviewed-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/4ddcc2e704fc6b1592a878c80e15fadd82c63550.1736345025.git.jani.nikula@intel.com
Signed-off-by: Jani Nikula <jani.nikula@intel.com>