dm: Use access methods for dev/uclass private data

Most drivers use these access methods but a few do not. Update them.

In some cases the access is not permitted, so mark those with a FIXME tag
for the maintainer to check.

Signed-off-by: Simon Glass <sjg@chromium.org>
Acked-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Acked-by: Pratyush Yadav <p.yadav@ti.com>
diff --git a/drivers/spi/soft_spi.c b/drivers/spi/soft_spi.c
index afc98bf..3425d99 100644
--- a/drivers/spi/soft_spi.c
+++ b/drivers/spi/soft_spi.c
@@ -228,7 +228,7 @@
 
 static int soft_spi_of_to_plat(struct udevice *dev)
 {
-	struct soft_spi_plat *plat = dev->plat;
+	struct soft_spi_plat *plat = dev_get_plat(dev);
 	const void *blob = gd->fdt_blob;
 	int node = dev_of_offset(dev);
 
@@ -240,7 +240,7 @@
 static int soft_spi_probe(struct udevice *dev)
 {
 	struct spi_slave *slave = dev_get_parent_priv(dev);
-	struct soft_spi_plat *plat = dev->plat;
+	struct soft_spi_plat *plat = dev_get_plat(dev);
 	int cs_flags, clk_flags;
 	int ret;