drm/panel: Add driver for the Sony ACX565AKM panel

This panel is used on the Nokia N900.

The code is based on the omapdrm-specific panel-sony-acx565akm driver.
The hardware-related logic has been changed as little as possible to
avoid regressions as hardware availability is lacking to test the
changes. Follow-up patches should address the items listed in the TODO
list.

v2:
- fix checkpatch warning (lcd == NULL) => (!lcd) (sam)

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Sam Ravnborg <sam@ravnborg.org>
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20190813201101.30980-8-laurent.pinchart@ideasonboard.com