board: brxre1: fix building errors

Fix building errors if CONFIG_DM_VIDEO is enabled. This is the only
u-boot board that enables CONFIG_AM335X_LCD and from which I started
to develop the version of the frame buffer driver that supports the
driver model.

Signed-off-by: Dario Binacchi <dariobin@libero.it>
diff --git a/include/configs/brxre1.h b/include/configs/brxre1.h
index ea15912..0066633 100644
--- a/include/configs/brxre1.h
+++ b/include/configs/brxre1.h
@@ -14,7 +14,9 @@
 #include <configs/bur_cfg_common.h>
 #include <configs/bur_am335x_common.h>
 /* ------------------------------------------------------------------------- */
+#if !defined(CONFIG_AM335X_LCD)
 #define CONFIG_AM335X_LCD
+#endif
 #define LCD_BPP				LCD_COLOR32
 
 /* memory */