board: tbs2910: Remove FIT support in defconfig to reduce u-boot size

The current defconfig build generates a u-boot.imx file that is too large
for the available space on a eMMC/SD card. Installing this file overwrites
the u-boot environment. So disable the unused FIT support to reduce the
size of the u-boot binary.

Signed-off-by: Soeren Moch <smoch@web.de>
diff --git a/configs/tbs2910_defconfig b/configs/tbs2910_defconfig
index 55cd9bd..fc15dcf 100644
--- a/configs/tbs2910_defconfig
+++ b/configs/tbs2910_defconfig
@@ -5,7 +5,6 @@
 CONFIG_TARGET_TBS2910=y
 CONFIG_CMD_HDMIDETECT=y
 CONFIG_NR_DRAM_BANKS=1
-CONFIG_FIT=y
 CONFIG_BOOTDELAY=3
 CONFIG_PRE_CONSOLE_BUFFER=y
 CONFIG_PRE_CON_BUF_ADDR=0x7c000000