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/test/dm/devres.c b/test/dm/devres.c
index e1e088a..00edbd0 100644
--- a/test/dm/devres.c
+++ b/test/dm/devres.c
@@ -158,7 +158,7 @@
 	ut_asserteq(1, stats.allocs);
 	ut_asserteq(TEST_DEVRES_SIZE, stats.total_size);
 
-	/* Getting platdata should add one allocation */
+	/* Getting plat should add one allocation */
 	ut_assertok(device_ofdata_to_platdata(dev));
 	devres_get_stats(dev, &stats);
 	ut_asserteq(2, stats.allocs);