drivers: Use CONFIG_XPL_BUILD instead of CONFIG_SPL_BUILD

Use the new symbol to refer to any 'SPL' build, including TPL and VPL

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/drivers/power/power_core.c b/drivers/power/power_core.c
index 1caf9f0..61b2fe5 100644
--- a/drivers/power/power_core.c
+++ b/drivers/power/power_core.c
@@ -78,7 +78,7 @@
 	return NULL;
 }
 
-#ifndef CONFIG_SPL_BUILD
+#ifndef CONFIG_XPL_BUILD
 static int pmic_dump(struct pmic *p)
 {
 	int i, ret;