db410c: add FIT support

1. Add FIT support for DB410c defconfig.
2. Don't overwrite bootargs (they're already
   defined in Linux device tree for DB410c.
Signed-off-by: NRamon Fried <ramon.fried@gmail.com>

configs/dragonboard410c_defconfig

@@ -4,9 +4,8 @@ CONFIG_SYS_TEXT_BASE=0x80080000
 CONFIG_IDENT_STRING="\nQualcomm-DragonBoard 410C"
 CONFIG_DEFAULT_DEVICE_TREE="dragonboard410c"
 CONFIG_DISTRO_DEFAULTS=y
+CONFIG_FIT=y
 CONFIG_OF_BOARD_SETUP=y
-CONFIG_USE_BOOTARGS=y
-CONFIG_BOOTARGS="console=ttyMSM0,115200n8"
 # CONFIG_DISPLAY_CPUINFO is not set
 # CONFIG_DISPLAY_BOARDINFO is not set
 CONFIG_SYS_PROMPT="dragonboard410c => "