wifi: ar5523: Remove unnecessary (void*) conversions

No need cast (void*) to (struct ar5523_cmd_hdr *).

Signed-off-by: Wu Yunchuan <yunchuan@nfschina.com>
Signed-off-by: Kalle Valo <quic_kvalo@quicinc.com>
Link: https://lore.kernel.org/r/20230919044906.523189-1-yunchuan@nfschina.com