iris: Replace no_gpu flag with PIPE_MAP_DIRECTLY

iris: Replace no_gpu flag with PIPE_MAP_DIRECTLY

Here, we're deciding when to map the buffer directly, rather than using
the GPU to blit to/from a temporary.  There is already a flag for that,
PIPE_MAP_DIRECTLY, which has the added benefit of not being a negative
(such as "no_gpu").

Currently, we intend to map directly if:

1. Direct mappings were requested explicitly
2. Persistent or coherent mappings were requested (and so we must)
3. ASTC textures (we currently can't blit those correctly)
4. There is no need for a temporary (there's no image compression that
   the CPU wouldn't understand, and we don't need to avoid stalls due
   to the buffer being busy on the GPU)

Expressing "please memory map this directly" is easier to follow than
"please don't use the GPU as part of mapping this".

Acked-by: Lionel Landwerlin <lionel.g.landwerlin@intel.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/10941>