drm/st7586: Use devm_drm_dev_alloc

Already using devm_drm_dev_init, so very simple replacment.
Acked-by: David Lechner <david@lechnology.com>
Acked-by: Sam Ravnborg <sam@ravnborg.org>
Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
Cc: David Lechner <david@lechnology.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200415074034.175360-15-daniel.vetter@ffwll.ch

drivers/gpu/drm/tiny/st7586.c

@@ -317,18 +317,13 @@ static int st7586_probe(struct spi_device *spi)
 	size_t bufsize;
 	int ret;
 
-	dbidev = kzalloc(sizeof(*dbidev), GFP_KERNEL);
-	if (!dbidev)
-		return -ENOMEM;
+	dbidev = devm_drm_dev_alloc(dev, &st7586_driver,
+				    struct mipi_dbi_dev, drm);
+	if (IS_ERR(dbidev))
+		return PTR_ERR(dbidev);
 
 	dbi = &dbidev->dbi;
 	drm = &dbidev->drm;
-	ret = devm_drm_dev_init(dev, drm, &st7586_driver);
-	if (ret) {
-		kfree(dbidev);
-		return ret;
-	}
-	drmm_add_final_kfree(drm, dbidev);
 
 	bufsize = (st7586_mode.vdisplay + 2) / 3 * st7586_mode.hdisplay;