colibri_imx6: adjust boot order

Remove duplicate of mmc0, set this boot order:
1) SD
2) eMMC
3) USB
4) DHCP boot

Fixes: 0e15165bc4e0 ("colibri_imx6: boot env configuration updates")
Signed-off-by: Igor Opaniuk <igor.opaniuk@toradex.com>
Signed-off-by: Oleksandr Suvorov <oleksandr.suvorov@toradex.com>
diff --git a/include/configs/colibri_imx6.h b/include/configs/colibri_imx6.h
index c014d6b..5f5e201 100644
--- a/include/configs/colibri_imx6.h
+++ b/include/configs/colibri_imx6.h
@@ -72,7 +72,6 @@
 
 #ifndef CONFIG_SPL_BUILD
 #define BOOT_TARGET_DEVICES(func) \
-	func(MMC, mmc, 0) \
 	func(MMC, mmc, 1) \
 	func(MMC, mmc, 0) \
 	func(USB, usb, 0) \