wifi: rtw89: refine link handling for link_sta_rc_update

The original handling will iterate all active links under the given sta
and apply the changes to each. Now, stack tweaks ops from sta_rc_update
to link_sta_rc_update, which means targeting a given link. Then, our link
iteration looks redundant. So, refine it to apply the changes to the link
directly.

Signed-off-by: Zong-Zhe Yang <kevin_yang@realtek.com>
Signed-off-by: Ping-Ke Shih <pkshih@realtek.com>
Link: https://patch.msgid.link/20241128055433.11851-6-pkshih@realtek.com