board: tbs2910: Enable distro_boot support.

This keeps the compatibility with the old bootcmd.

The fdtfile environment variable also needed to be set to
imx6q-tbs2910.dtb to enable booting mainline kernels
otherwise with extlinux.conf it tries to load
mx6-tbs2910.dtb instead.

With arm-linux-gnueabi-gcc 9.2.0-1 from the Parabola
GNU/Linux distribution, we have the following size
differences:
- text: +2041 bytes
- data: 0 bytes
- bss: 0 bytes
- total: +2041 bytes

Signed-off-by: Denis 'GNUtoo' Carikli <GNUtoo@cyberdimension.org>
Reviewed-by: Soeren Moch <smoch@web.de>
diff --git a/configs/tbs2910_defconfig b/configs/tbs2910_defconfig
index fc9095c..fbd2293 100644
--- a/configs/tbs2910_defconfig
+++ b/configs/tbs2910_defconfig
@@ -12,11 +12,12 @@
 CONFIG_ENV_VARS_UBOOT_CONFIG=y
 CONFIG_BOOTDELAY=3
 CONFIG_USE_BOOTCOMMAND=y
-CONFIG_BOOTCOMMAND="mmc rescan; if run bootcmd_up1; then run bootcmd_up2; else run bootcmd_mmc; fi"
+CONFIG_BOOTCOMMAND="mmc rescan; if run bootcmd_up1; then run bootcmd_up2; else run bootcmd_mmc || run distro_bootcmd; fi"
 CONFIG_USE_PREBOOT=y
 CONFIG_PREBOOT="echo PCI:; pci enum; pci 1; usb start; if hdmidet; then run set_con_hdmi; else run set_con_serial; fi"
 CONFIG_PRE_CONSOLE_BUFFER=y
 CONFIG_SUPPORT_RAW_INITRD=y
+CONFIG_DEFAULT_FDT_FILE="imx6q-tbs2910.dtb"
 CONFIG_BOUNCE_BUFFER=y
 CONFIG_BOARD_EARLY_INIT_F=y
 CONFIG_HUSH_PARSER=y