dm: treewide: Rename 'platdata' variables to just 'plat'

We use 'priv' for private data but often use 'platdata' for platform data.
We can't really use 'pdata' since that is ambiguous (it could mean private
or platform data).

Rename some of the latter variables to end with 'plat' for consistency.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/include/cpu.h b/include/cpu.h
index 78e88b9..1d53308 100644
--- a/include/cpu.h
+++ b/include/cpu.h
@@ -17,7 +17,7 @@
  * @timebase_freq: the current frequency at which the cpu timer timebase
  *		   registers are updated (in Hz)
  *
- * This can be accessed with dev_get_parent_platdata() for any UCLASS_CPU
+ * This can be accessed with dev_get_parent_plat() for any UCLASS_CPU
  * device.
  */
 struct cpu_platdata {