arm64: adjust axxia uImage loadaddr and entryaddr to 2M align

Now the loadaddr and entryaddr for uImage of axm56xx is 0x80000 and
this will trigger the kernel warning as below:

[    0.000000] [Firmware Bug]: Kernel image misaligned at boot, please fix your bootloader!

Adjust addrs to 2M align to fix this.

Signed-off-by: Quanyang Wang <quanyang.wang@windriver.com>
Signed-off-by: Bruce Ashfield <bruce.ashfield@gmail.com>