wifi: rtl8xxxu: fix authentication timeout due to incorrect RCR value

[ Upstream commit 20429444

 ]

When using rtl8192cu with rtl8xxxu driver to connect wifi, there is a
probability of failure, which shows "authentication with ... timed out".
Through debugging, it was found that the RCR register has been inexplicably
modified to an incorrect value, resulting in the nic not being able to
receive authenticated frames.

To fix this problem, add regrcr in rtl8xxxu_priv struct, and store
the RCR value every time the register is written, and use it the next
time the register need to be modified.

Signed-off-by: Yun Lu <luyun@kylinos.cn>
Link: https://lore.kernel.org/all/20230427020512.1221062-1-luyun_611@163.com
Signed-off-by: Kalle Valo <kvalo@kernel.org>
Link: https://lore.kernel.org/r/20230512012055.2990472-1-luyun_611@163.com
Signed-off-by: Sasha Levin <sashal@kernel.org>