rtlwifi: rtl8192ee: Make driver support 64bits DMA.

1. Both 32-bit and 64-bit use the same TX/RX buffer desc layout
2. Extend set_desc() and get_desc() to set and get 64-bit address
3. Remove directive DMA_IS_64BIT
4. Add module parameter to turn on 64-bit dma

Signed-off-by: Ping-Ke Shih <pkshih@realtek.com>
Signed-off-by: Larry Finger <Larry.Finger@lwfinger.net>
Cc: Yan-Hsuan Chuang <yhchuang@realtek.com>
Cc: Birming Chiu <birming@realtek.com>
Cc: Shaofu <shaofu@realtek.com>
Cc: Steven Ting <steventing@realtek.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>