dm: treewide: Rename ..._platdata variables to just ..._plat

Try to maintain some consistency between these variables by using _plat as
a suffix for them.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/drivers/spi/tegra_spi.h b/drivers/spi/tegra_spi.h
index e997d66..ab69ea4 100644
--- a/drivers/spi/tegra_spi.h
+++ b/drivers/spi/tegra_spi.h
@@ -3,7 +3,7 @@
  * (C) Copyright 2014 Google, Inc
  */
 
-struct tegra_spi_platdata {
+struct tegra_spi_plat {
 	enum periph_id periph_id;
 	int frequency;		/* Default clock frequency, -1 for none */
 	ulong base;