isl: changes to support display requirement on compressed surfaces

While working with a colleague on testing modifiers on a new platform that is introducing alignment requirement for the CCS plane, I came up with those 2 changes that look generic enough to go in main.

The idea is to have the usage of the main surface also available in the compressed one. I couldn't see any problematic bits that should be filtered off the main surface.

With this we can then add finer checks in isl_surf_init_s() to apply CCS alignment constraints.