ktls: Use COUNTER_U64_DEFINE_EARLY for the ktls_toe_chacha20 counter.

I missed updating this counter when rebasing the changes in
9c64fc40290e08f6dc6b75aa04084b04e48a61af after the switch to
COUNTER_U64_DEFINE_EARLY in 1755b2b9891bb1bfa7a58383ef5126821f7e46e3.

Fixes: 9c64fc40290e Add Chacha20-Poly1305 as a KTLS cipher suite.
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