arm64: Trap PIE builds early if load address is not 4K aligned

arm64: Trap PIE builds early if load address is not 4K aligned

PIE requires a 4K aligned load address. If this is not met, trap
the startup sequence in a WFI loop rather than running into obscure
failures.

Tested-by: Michal Simek <michal.simek@xilinx.com>
Suggested-by: André Przywara <andre.przywara@arm.com>
Signed-off-by: Edgar E. Iglesias <edgar.iglesias@xilinx.com>
Reviewed-by: Stephen Warren <swarren@nvidia.com>
Signed-off-by: Michal Simek <michal.simek@xilinx.com>