Silicon/ARM/N1SoC: Add platform library implementation

Add the initial Arm's Neoverse N1 System-on-Chip platform library
support. This includes the virtual memory map and helper functions for
platform initialization.

Cc: Ard Biesheuvel <ard.biesheuvel@arm.com>
Cc: Leif Lindholm <leif@nuviainc.com>
Signed-off-by: Pranav Madhu <pranav.madhu@arm.com>
Reviewed-by: Thomas Abraham <thomas.abraham@arm.com>
Reviewed-by: Leif Lindholm <leif@nuviainc.com>