anv: Align fast clear color state buffer to a page.

anv: Align fast clear color state buffer to a page.

On gen11 and older, compressed images are tiled and aligned to 4K. On
gen12 this 4K alignment restriction was removed. However, only aligning
the fast clear color buffer to 64B (a cacheline, as it's on the
documentation) is causing some bugs where the fast clear color is not
converted during the fast clear operation. Aligning things to 4K seems
to fix it.

v2: Assert that image->planes[plane].offset is 4K aligned (Nanley)

Reviewed-by: Nanley Chery <nanley.g.chery@intel.com>