tc: move Linux to 2MiB above ram start

Linux has a requirement to be loaded at 2 MiB aligned address. To
comply, u-boot will accept any load address and quietly move it to such
an address. For whatever reason the load address on the FVP isn't 2MiB
aligned but is fairly close so we needlessly lose time.

Move the address to 2MiB above the start of ram to simplify u-boot's
job. This also aligns the FVP with the FPGA and enables a unified
u-boot.

Signed-off-by: Boyan Karatotev <boyan.karatotev@arm.com>