Replace the flags/hint arguments to bo_alloc{,_static} with a location mask.

Replace the flags/hint arguments to bo_alloc{,_static} with a location mask.

Now, allocations only take locations, rather than a variety of unused flags.
The only interesting flag before was the no_move/no_evict pair for scanout
and similar buffers, which the DRI drivers don't use.  That will be readded
when we get to using this code for display buffer allocation, by adding a
pin/unpin call (dynamic pinning/unpinning may be useful for VT switching and
root window resizing).

This commit changes one instance of DRM_BO_FLAG_MEM_LOCAL with
DRM_BO_FLAG_MEM_TT, which appeared to have been unintentional.