i965: Split per miptree and per slice/level fast clear bits

i965: Split per miptree and per slice/level fast clear bits

Currently the status bits for fast clear include the flag telling
if non-multisampled mcs buffer should be used at all. Once the
state tracking is changed to follow individual levels/layers one
still needs to have the mcs enabling information in the miptree.
Therefore simply split it out to its own boolean.

Possible follow-up work is to combine disable_aux_buffers and
no_ccs into single enum.

v2 (Jason): Changed no_msrt_mcs to no_ccs and updated comment

Signed-off-by: Topi Pohjolainen <topi.pohjolainen@intel.com>
Reviewed-by: Jason Ekstrand <jason@jlekstrand.net>