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/sdhci.h b/include/sdhci.h
index d04afd5..69c2087 100644
--- a/include/sdhci.h
+++ b/include/sdhci.h
@@ -440,7 +440,7 @@
  * ...
  *
  * Inside U_BOOT_DRIVER():
- *	.platdata_auto	= sizeof(struct msm_sdhc_plat),
+ *	.plat_auto	= sizeof(struct msm_sdhc_plat),
  *
  * To access platform data:
  *	struct msm_sdhc_plat *plat = dev_get_platdata(dev);