image-size: Increase non secure image size

-Increase the non-secure image size from 0x330000 to 0x340000 in
corstone-300 as after the addition of the changes of this branch
some images sizes may exceed the old size.

-No need to modify Corstone-310 non secure images size as it is
already set to 0x340000.

Check the following run for reference:
https://gitlab.oss.arm.com/engineering/iot-m-sw/open-iot-sdk/


examples/total-solutions/-/jobs/1937952

Signed-off-by: Ahmed.Ismail <Ahmed.Ismail@arm.com>