drm/arm: arm hdlcd select DRM_GEM_CMA_HELPER

Without DRM_GEM_CMA_HELPER HDLCD won't build. This needs to be there too.

Fixes: 09717af7

 ("drm: Remove CONFIG_DRM_KMS_CMA_HELPER option")
Reviewed-by: Steven Price <steven.price@arm.com>
Signed-off-by: Carsten Haitzler <carsten.haitzler@arm.com>
Acked-by: Liviu Dudau <liviu.dudau@arm.com>
Signed-off-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20220124162437.2470344-1-carsten.haitzler@foss.arm.com