tbs2910: add CONFIG_SUPPORT_EMMC_BOOT

Add emmc boot partition commands to be able to select the boot partition.

Signed-off-by: Soeren Moch <smoch@web.de>

include/configs/tbs2910.h

@@ -102,6 +102,7 @@
 #define CONFIG_MMC
 #define CONFIG_CMD_MMC
 #define CONFIG_GENERIC_MMC
+#define CONFIG_SUPPORT_EMMC_BOOT
 #define CONFIG_BOUNCE_BUFFER
 
 /* Ethernet */