drm/panel: use 'select' for Ili9341 panel driver helpers

Use 'select' instead of 'depends on' for DRM helpers for the
Ilitek ILI9341 panel driver.
This is what is done in the vast majority of other cases and
this makes it possible to fix a build error with drm_mipi_dbi.

Fixes: 5a042273 ("drm/panel: Add ilitek ili9341 panel driver")
Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Cc: Dillon Min <dillon.minfei@gmail.com>
Cc: Linus Walleij <linus.walleij@linaro.org>
Cc: Sam Ravnborg <sam@ravnborg.org>
Cc: Noralf Trønnes <noralf@tronnes.org>
Cc: Thomas Zimmermann <tzimmermann@suse.de>
Cc: Thierry Reding <thierry.reding@gmail.com>
Cc: dri-devel@lists.freedesktop.org
Cc: David Airlie <airlied@linux.ie>
Cc: Daniel Vetter <daniel@ffwll.ch>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20220823004227.10820-1-rdunlap@infradead.org