rtlwifi: rtl8192de: Fix misleading REG_MCUFWDL information

RT_TRACE shows REG_MCUFWDL value as a decimal value with a '0x'
prefix, which is somewhat misleading.

Fix it to print hexadecimal, as was intended.

Cc: Ping-Ke Shih <pkshih@realtek.com>
Cc: Kalle Valo <kvalo@codeaurora.org>
Signed-off-by: Shaokun Zhang <zhangshaokun@hisilicon.com>
Acked-by: Ping-Ke Shih <pkshih@realtek.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>