dt-bindings: clock: ast2600: Expand comment on reset definitions

dt-bindings: clock: ast2600: Expand comment on reset definitions

The current "not part of a gate" is a little ambiguous. Expand this a
little to clarify the reference to the paired clock + reset control.

Signed-off-by: Jeremy Kerr <jk@codeconstruct.com.au>
Link: https://lore.kernel.org/r/20230302005834.13171-7-jk@codeconstruct.com.au
Reviewed-by: Joel Stanley <joel@jms.id.au>
Acked-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Tested-by: Joel Stanley <joel@jms.id.au>
Signed-off-by: Stephen Boyd <sboyd@kernel.org>