wifi: mwifiex: simplify mwifiex_setup_ht_caps()

wifi: mwifiex: simplify mwifiex_setup_ht_caps()

In mwifiex_setup_ht_caps() first a local struct ieee80211_mcs_info
is initialized and afterwards copied over &ht_info->mcs. Simplify
this by initializing &ht_info->mcs directly.

While at it call memset on the u8 rx_mask[] array instead of the struct
which makes the intention clearer and we no longer have to assume the
rx_mask array is the first member of struct ieee80211_mcs_info.

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
Acked-by: Brian Norris <briannorris@chromium.org>
Reviewed-by: Jeff Chen <jeff.chen_1@nxp.com>
Link: https://patch.msgid.link/20250410-mwifiex-cleanup-1-v6-6-a6bbd4ac4d37@pengutronix.de
Signed-off-by: Johannes Berg <johannes.berg@intel.com>