rtw88: fix RX clock gate setting while fifo dump

When fw fifo dumps, RX clock gating should be disabled to avoid
something unexpected. However, the register operation ran into
a mistake. So, we fix it.

Signed-off-by: Zong-Zhe Yang <kevin_yang@realtek.com>
Signed-off-by: Ping-Ke Shih <pkshih@realtek.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
Link: https://lore.kernel.org/r/20210927111830.5354-1-pkshih@realtek.com