wifi: ath9k: Remove unnecessary (void*) conversions

No need cast (void *) to (struct owl_ctx *), (struct ath_hw *),
(struct cmd_buf *) or other types.

Signed-off-by: Wu Yunchuan <yunchuan@nfschina.com>
Reviewed-by: Jeff Johnson <quic_jjohnson@quicinc.com>
Acked-by: Toke Høiland-Jørgensen <toke@toke.dk>
Signed-off-by: Kalle Valo <quic_kvalo@quicinc.com>
Link: https://lore.kernel.org/r/20230919045226.524544-1-yunchuan@nfschina.com