radeonsi: rename cache flushing flags once more

radeonsi: rename cache flushing flags once more

KCACHE, TC L1 and TC L2 are renamed to:
- SMEM L1
- VMEM L1
- GLOBAL L2

You can easily tell what they are used for now.
Shaders must deal with coherency issues between both L1s manually,
e.g. by setting GLC=1 or by using s_dcache_*.

BOTH_ICACHE_KCACHE was an unused definition.

Reviewed-by: Nicolai Hähnle <nicolai.haehnle@amd.com>