arch-arm, configs: Treat the bootloader rom as cacheable memory

Prior to this changeset the bootloader rom (instantiated as a
SimpleMemory) in ruby Arm systems was treated as an IO device and it
was fronted by a DMA controller. This changeset moves the bootloader
rom and adds it to the system as another memory with a dedicated
directory controller.

Change-Id: I094fed031cdef7f77a939d94f948d967b349b7e0
Reviewed-by: Andreas Sandberg <andreas.sandberg@arm.com>
Reviewed-on: https://gem5-review.googlesource.com/8741
Reviewed-by: Jason Lowe-Power <jason@lowepower.com>
Maintainer: Jason Lowe-Power <jason@lowepower.com>

tests/configs/base_config.py

@@ -170,8 +170,9 @@ class BaseSystem(object):
             options.num_cpus = self.num_cpus
             options.num_dirs = 2
 
+            bootmem = getattr(system, 'bootmem', None)
             Ruby.create_system(options, True, system, system.iobus,
-                               system._dma_ports)
+                               system._dma_ports, bootmem)
 
             # Create a seperate clock domain for Ruby
             system.ruby.clk_domain = SrcClockDomain(