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/ddr/altera/sdram_gen5.c b/drivers/ddr/altera/sdram_gen5.c
index 3ffe057..8d3ce49 100644
--- a/drivers/ddr/altera/sdram_gen5.c
+++ b/drivers/ddr/altera/sdram_gen5.c
@@ -565,7 +565,7 @@
 
 static int altera_gen5_sdram_of_to_plat(struct udevice *dev)
 {
-	struct altera_gen5_sdram_plat *plat = dev->plat;
+	struct altera_gen5_sdram_plat *plat = dev_get_plat(dev);
 
 	plat->sdr = (struct socfpga_sdr *)devfdt_get_addr_index(dev, 0);
 	if (!plat->sdr)
@@ -578,7 +578,7 @@
 {
 	int ret;
 	unsigned long sdram_size;
-	struct altera_gen5_sdram_plat *plat = dev->plat;
+	struct altera_gen5_sdram_plat *plat = dev_get_plat(dev);
 	struct altera_gen5_sdram_priv *priv = dev_get_priv(dev);
 	struct socfpga_sdr_ctrl *sdr_ctrl = &plat->sdr->sdr_ctrl;
 	struct reset_ctl_bulk resets;