Enable programming pat indexes on mtl linux for device buffers.
Change DrmMemoryManager::allocateMemoryByKMD to use gemCreateExt.
Set mmap flags based on coherency.
Map as write back on legacy and coherent.
On non-coherent map as write combined.
Changes currently disabled, to enable use debug keys:
DisableGemCreateExtSetPat=0
UseGemCreateExtInAllocateMemoryByKMD=1
Reorder BufferObject to decrease padding.
Related-To: NEO-7896
Signed-off-by: Dominik Dabek <dominik.dabek@intel.com>