anv: Add driconf option to disable compression for 16bpp format

On Fallout4, enabling HIZ_CCS_WT compression for D16_UNORM format
regress the performance by 2%, in order to avoid that disable
compression via driconf option.

The experiment showed that, running Fallout4 with HIZ performs better
than HIZ_CCS and HIZ_CCS_WT. Reason behind that is the benchmark uses
the depth pass with D16_UNORM surfaces format which fills the L3 cache
and next pass doesn't make use of it where we end up clearing cache.

v2:
- Don't add conditional check in isl (Nanley, Jason)
- Move disable_d16unorm_compression flag to instance (Lionel)
- Use plane_format.isl_format (Nanley)

v3:
- Add more descriptive comment (Marcin Ślusarz)

Signed-off-by: Sagar Ghuge <sagar.ghuge@intel.com>
Reviewed-by: Lionel Landwerlin <lionel.g.landwerlin@intel.com>
Part-of: <!6734>