shift6mq: Switch to rm69299 downstream panel driver

The driver upstreamed by @kcxt is in 6.17. I've picked some changes from drm-misc-next in an extra commit so they autodiscard on rebase. For the mainline driver to work we have to revert the reset GPIO polarity change. The only not mainline change is

drm/panel: visionox-rm69299: Set prepare_prev_first

which idk if it should go upstream or if it is a result of how currently the display pipeline is setup here.

With that applied we can drop the downstream driver:

$ git diff --stat 6.17-wip -- drivers/gpu/drm/panel/
 drivers/gpu/drm/panel/Kconfig                        |   9 -
 drivers/gpu/drm/panel/panel-visionox-rm69299-shift.c | 708 ---------------------------------------------------------------------
 drivers/gpu/drm/panel/panel-visionox-rm69299.c       |  72 ++++++-
 3 files changed, 70 insertions(+), 719 deletions(-)