wifi: rtw89: 8852c: rfk: correct miscoding delay of DPK

Using mdelay() can work well, but calibration causes too much time. Use
proper udelay() to get shorter time and the same result.

Signed-off-by: Ping-Ke Shih <pkshih@realtek.com>
Signed-off-by: Kalle Valo <kvalo@kernel.org>
Link: https://lore.kernel.org/r/20220930133318.6335-2-pkshih@realtek.com