mx28evk: Provide default values for SPI bus and chip select

Provide default values for SPI bus and chip select.

This allows the command "sf probe" to work without passing SPI bus and chip
select numbers as arguments.

Signed-off-by: Fabio Estevam <fabio.estevam@freescale.com>
Acked-by: Marek Vasut <marex@denx.de>

include/configs/mx28evk.h

@@ -186,6 +186,8 @@
 /* SPI Flash */
 #ifdef CONFIG_CMD_SF
 #define CONFIG_SPI_FLASH
+#define CONFIG_SF_DEFAULT_BUS	2
+#define CONFIG_SF_DEFAULT_CS	0
 /* this may vary and depends on the installed chip */
 #define CONFIG_SPI_FLASH_SST
 #define CONFIG_SF_DEFAULT_MODE		SPI_MODE_0