removing fdt_high from default set of variables for, dragonboard410c config

When using fitImage in AARCH64, the fdt is only 4 byte aligned.
According to linux kernel -> Documentation/arm64/booting.txt, the
fdt *must* be 8 byte aligned. Therefore, it is somewhat random,
if you build a kernel that the fdt is 4 or 8 byte aligned.
Removing fdt_high (or changing it to a valid 8 byte aligned
address) solves this issue.
Signed-off-by: NMatthias Schoepfer <matthias.schoepfer@ithinx.io>
CC: Mateusz Kulikowski <mateusz.kulikowski@gmail.com>

include/configs/dragonboard410c.h

@@ -69,7 +69,6 @@ REFLASH(dragonboard/u-boot.img, 8)\
 #define CONFIG_EXTRA_ENV_SETTINGS \
 	"reflash="CONFIG_ENV_REFLASH"\0"\
 	"loadaddr=0x81000000\0" \
-	"fdt_high=0xffffffffffffffff\0" \
 	"initrd_high=0xffffffffffffffff\0" \
 	"linux_image=Image\0" \
 	"kernel_addr_r=0x81000000\0"\