fdt: Drop SPL_BUILD macro

This old macro is not needed anymore since we can use IS_ENABLED() now.
Drop it.

Signed-off-by: Simon Glass <sjg@chromium.org>

drivers/serial/serial-uclass.c

@@ -104,7 +104,8 @@ static void serial_find_console_or_panic(void)
 			}
 		}
 	}
-	if (!SPL_BUILD || !CONFIG_IS_ENABLED(OF_CONTROL) || !blob) {
+	if (!IS_ENABLED(CONFIG_SPL_BUILD) || !CONFIG_IS_ENABLED(OF_CONTROL) ||
+	    !blob) {
 		/*
 		 * Try to use CONFIG_CONS_INDEX if available (it is numbered
 		 * from 1!).

include/fdtdec.h

@@ -49,12 +49,6 @@ struct fdt_memory {
 
 struct bd_info;
 
-#ifdef CONFIG_SPL_BUILD
-#define SPL_BUILD	1
-#else
-#define SPL_BUILD	0
-#endif
-
 /**
  * enum fdt_source_t - indicates where the devicetree came from
  *