intel/blorp: Use linear formats for CCS_E clear colors in copies

intel/blorp: Use linear formats for CCS_E clear colors in copies

It's clear that the original code meant to do this and there is even a
10-line comment explaining why.  Originally, we had a simple function
for packing the clear colors which was unaware of sRGB.  However, in
a6b66a7b26ae1, when we started using ISL to do the packing, the wrong
format was used.

Fixes: a6b66a7b26 "intel/blorp: Use ISL instead of bitcast_color..."
Reviewed-by: Topi Pohjolainen <topi.pohjolainen@intel.com>