- added "xscale fast_memory_access" which speeds up memory

 access by disabling "unecessary" checks.
- arm926ejs. Added missing type->mmu and type->virt2phys fn's.
 for now these are used by working_area when specifying
 mmu enabled and mmu not enabled address

git-svn-id: svn://svn.berlios.de/openocd/trunk@335 b42882b7-edfa-0310-969c-e2dbd0fdcd60