[TEMP] etnaviv: Don't apply pgprot_noncached for ETNA_BO_UNCACHED

Otherwise userspace gets a bus error since device memory (nGnRnE) is not
mappable.

This is an interims solution, see below link.

Link: https://lists.freedesktop.org/archives/etnaviv/2018-September/001946.htmlSigned-off-by: Guido Günther <guido.gunther@puri.sm>

drivers/gpu/drm/etnaviv/etnaviv_gem.c

@@ -133,10 +133,8 @@ static int etnaviv_gem_mmap_obj(struct etnaviv_gem_object *etnaviv_obj,
 
 	vm_page_prot = vm_get_page_prot(vma->vm_flags);
 
-	if (etnaviv_obj->flags & ETNA_BO_WC) {
+	if (etnaviv_obj->flags & (ETNA_BO_WC | ETNA_BO_UNCACHED)) {
 		vma->vm_page_prot = pgprot_writecombine(vm_page_prot);
-	} else if (etnaviv_obj->flags & ETNA_BO_UNCACHED) {
-		vma->vm_page_prot = pgprot_noncached(vm_page_prot);
 	} else {
 		/*
 		 * Shunt off cached objs to shmem file so they have their own