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/zynq_qspi.c b/drivers/spi/zynq_qspi.c
index 2fc28b6..845f2d2 100644
--- a/drivers/spi/zynq_qspi.c
+++ b/drivers/spi/zynq_qspi.c
@@ -100,7 +100,7 @@
 
 static int zynq_qspi_of_to_plat(struct udevice *bus)
 {
-	struct zynq_qspi_plat *plat = bus->plat;
+	struct zynq_qspi_plat *plat = dev_get_plat(bus);
 	const void *blob = gd->fdt_blob;
 	int node = dev_of_offset(bus);
 
@@ -592,7 +592,7 @@
 
 static int zynq_qspi_set_speed(struct udevice *bus, uint speed)
 {
-	struct zynq_qspi_plat *plat = bus->plat;
+	struct zynq_qspi_plat *plat = dev_get_plat(bus);
 	struct zynq_qspi_priv *priv = dev_get_priv(bus);
 	struct zynq_qspi_regs *regs = priv->regs;
 	uint32_t confr;