drm/mediatek: Introduce GEM object functions

GEM object functions deprecate several similar callback interfaces in
struct drm_driver. This patch replaces the per-driver callbacks with
per-instance callbacks in mediatek. The only exception is gem_prime_mmap,
which is non-trivial to convert.

Signed-off-by: Thomas Zimmermann <[e-mail]>
Reviewed-by: Daniel Vetter <[e-mail]>
Signed-off-by: Chun-Kuang Hu <[e-mail]>

drivers/gpu/drm/mediatek/mtk_drm_drv.c

···
 static struct drm_driver mtk_drm_driver = {
 	.driver_features = DRIVER_MODESET | DRIVER_GEM | DRIVER_ATOMIC,
 
-	.gem_free_object_unlocked = mtk_drm_gem_free_object,
-	.gem_vm_ops = &drm_gem_cma_vm_ops,
 	.dumb_create = mtk_drm_gem_dumb_create,
 
 	.prime_handle_to_fd = drm_gem_prime_handle_to_fd,
 	.prime_fd_to_handle = drm_gem_prime_fd_to_handle,
 	.gem_prime_import = mtk_drm_gem_prime_import,
-	.gem_prime_get_sg_table = mtk_gem_prime_get_sg_table,
 	.gem_prime_import_sg_table = mtk_gem_prime_import_sg_table,
 	.gem_prime_mmap = mtk_drm_gem_mmap_buf,
-	.gem_prime_vmap = mtk_drm_gem_prime_vmap,
-	.gem_prime_vunmap = mtk_drm_gem_prime_vunmap,
 	.fops = &mtk_drm_fops,
 
 	.name = DRIVER_NAME,

drivers/gpu/drm/mediatek/mtk_drm_gem.c

···
 #include <drm/drm.h>
 #include <drm/drm_device.h>
 #include <drm/drm_gem.h>
+#include <drm/drm_gem_cma_helper.h>
 #include <drm/drm_prime.h>
 
 #include "mtk_drm_drv.h"
 #include "mtk_drm_gem.h"
+
+static const struct drm_gem_object_funcs mtk_drm_gem_object_funcs = {
+	.free = mtk_drm_gem_free_object,
+	.get_sg_table = mtk_gem_prime_get_sg_table,
+	.vmap = mtk_drm_gem_prime_vmap,
+	.vunmap = mtk_drm_gem_prime_vunmap,
+	.vm_ops = &drm_gem_cma_vm_ops,
+};
 
 static struct mtk_drm_gem_obj *mtk_drm_gem_init(struct drm_device *dev,
 						unsigned long size)
···
 	mtk_gem_obj = kzalloc(sizeof(*mtk_gem_obj), GFP_KERNEL);
 	if (!mtk_gem_obj)
 		return ERR_PTR(-ENOMEM);
+
+	mtk_gem_obj->base.funcs = &mtk_drm_gem_object_funcs;
 
 	ret = drm_gem_object_init(dev, &mtk_gem_obj->base, size);
 	if (ret < 0) {