wifi: rtw88: Fix download_firmware_validate() for RTL8814AU

After the firmware is uploaded, download_firmware_validate() checks some
bits in REG_MCUFW_CTRL to see if everything went okay. The
RTL8814AU power on sequence sets bits 13 and 12 to 2, which this
function does not expect, so it thinks the firmware upload failed.

Make download_firmware_validate() ignore bits 13 and 12.

Signed-off-by: Bitterblue Smith <rtl8821cerfe2@gmail.com>
Acked-by: Ping-Ke Shih <pkshih@realtek.com>
Signed-off-by: Ping-Ke Shih <pkshih@realtek.com>
Link: https://patch.msgid.link/049d2887-22fc-47b7-9e59-62627cb525f8@gmail.com