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/adc.c b/test/dm/adc.c
index 8c6e4b0..740167e 100644
--- a/test/dm/adc.c
+++ b/test/dm/adc.c
@@ -67,7 +67,7 @@
 	ut_assertok(regulator_set_value(supply, SANDBOX_BUCK2_SET_UV));
 	ut_asserteq(SANDBOX_BUCK2_SET_UV, regulator_get_value(supply));
 
-	/* Update ADC platdata and get new Vdd value */
+	/* Update ADC plat and get new Vdd value */
 	ut_assertok(adc_vdd_value(dev, &uV));
 	ut_asserteq(SANDBOX_BUCK2_SET_UV, uV);