wifi: rtw89: 8852b: fix definition of KIP register number

An incorrect definition caused DPK to fail to backup and
restore a set of KIP registers. Fixing this will improve
RX throughput from 902 to 997 Mbps.

Fixes: 5b8471ac ("wifi: rtw89: 8852b: rfk: add DPK")
Signed-off-by: Kuan-Chung Chen <damon.chen@realtek.com>
Signed-off-by: Ping-Ke Shih <pkshih@realtek.com>
Link: https://patch.msgid.link/20240621123617.6687-2-pkshih@realtek.com