ARM: ti: Increase the allocated size for MLO.raw

MLO has increased to a size greater than the allocated
128 kB in dfu_alt_info_emmc and _mmc.

Therefore, double the allocated size for MLO.raw in
the default environment.

Signed-off-by: Faiz Abbas <faiz_abbas@ti.com>
Signed-off-by: Aswath Govindraju <a-govindraju@ti.com>
Signed-off-by: Lokesh Vutla <lokeshvutla@ti.com>
Link: https://lore.kernel.org/r/20210419065027.5834-1-a-govindraju@ti.com