wifi: rtw89: mcc: pass whom to stop at when pausing chanctx

When stopping MCC, FW can stop at a given MCC role following H2C command.
When pausing chanctx during MCC, in general, the caller expects to process
things with its chanctx. So, pass the caller as target and let FW stop MCC
at it.

Signed-off-by: Zong-Zhe Yang <kevin_yang@realtek.com>
Signed-off-by: Ping-Ke Shih <pkshih@realtek.com>
Link: https://patch.msgid.link/20250511035217.10410-2-pkshih@realtek.com