drm/panel/raydium-rm692e5: select CONFIG_DRM_DISPLAY_DP_HELPER

As with several other panel drivers, this fails to link without the DP
helper library:

ld: drivers/gpu/drm/panel/panel-raydium-rm692e5.o: in function `rm692e5_prepare':
panel-raydium-rm692e5.c:(.text+0x11f4): undefined reference to `drm_dsc_pps_payload_pack'

Select the same symbols that the others already use.

Fixes: 988d0ff2

 ("drm/panel: Add driver for BOE RM692E5 AMOLED panel")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Reviewed-by: Neil Armstrong <neil.armstrong@linaro.org>
Link: https://lore.kernel.org/r/20231023115619.3551348-1-arnd@kernel.org
Signed-off-by: Neil Armstrong <neil.armstrong@linaro.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20231023115619.3551348-1-arnd@kernel.org