isl: Drop WaDisableSamplerL2BypassForTextureCompressedFormats on Gen11

Gen11 doesn't require us to bypass the L2 cache for BC* images anymore.

The documentation is a bit hard to follow on this point, but the Windows
driver clearly only applies this workaround on Gen9, and their commit
history indicates that this was an intentional change to drop the
workaround for Gen11+.

Reviewed-by: Jason Ekstrand <jason@jlekstrand.net>
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merge request