board: tbs2910: Fix BOOTMAPSZ
The linux kernel imx_v6_v7_defconfig sets the user/kernel memory split
to 3G/1G now (was 2G/2G before). We have to adapt the BOOTMAPSZ so that
the decompressor finds zImage and dtb in lowmem.
Signed-off-by: Soeren Moch <smoch@web.de>
Soeren Moch