drm/etnaviv: Request pages from DMA32 zone on addressing_limited

Remove __GFP_HIGHMEM when requesting a page from DMA32 zone,
and since all vivante GPUs in the system will share the same
DMA constraints, move the check of whether to get a page from
DMA32 to etnaviv_bind().

Fixes: b72af445 ("drm/etnaviv: request pages from DMA32 zone when needed")
Suggested-by: Sui Jingfeng <sui.jingfeng@linux.dev>
Signed-off-by: Xiaolei Wang <xiaolei.wang@windriver.com>
Reviewed-by: Christian Gmeiner <cgmeiner@igalia.com>
Signed-off-by: Lucas Stach <l.stach@pengutronix.de>