Minimal ARM LPAE support. Sufficient to boot Linux kernel on vexpress-a15
Missing: * Extends the DBGDRAR and DBGDSAR to 64 bits, to hold PAs of up to 40 bits. * Defines two Memory Attribute Indirection Registers, MAIRn, to replace PRRR and NMRR when using the Long-descriptor translation table format. * Provides two IMPLEMENTATION DEFINED Auxiliary Memory Attribute Indirection Registers 0 AMAIRn. Does not change behaviour of Short-descriptor format (AKA _v6)
