video, lg4573: make spi bus and cs configurable

make the spi bus and the spi chipselect configurable
for the lg4573 driver. Use it on the aristainetos
boards.

Signed-off-by: Heiko Schocher <hs@denx.de>
Acked-by: Anatolij Gustschin <agust@denx.de>
diff --git a/drivers/video/lg4573.c b/drivers/video/lg4573.c
index 43670fc..11fef27 100644
--- a/drivers/video/lg4573.c
+++ b/drivers/video/lg4573.c
@@ -220,7 +220,8 @@
 static int do_lgset(cmd_tbl_t *cmdtp, int flag, int argc,
 		       char * const argv[])
 {
-	lg4573_spi_startup(0, 0, 10000000, SPI_MODE_0);
+	lg4573_spi_startup(CONFIG_LG4573_BUS, CONFIG_LG4573_CS, 10000000,
+			   SPI_MODE_0);
 	return 0;
 }