wifi: rtl8xxxu: Simplify the error handling code

Since the logic of the driver's error handling code has changed, the
previous dead store and checks are not needed.

Reported-by: kernel test robot <lkp@intel.com>
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Zheyu Ma <zheyuma97@gmail.com>
Signed-off-by: Kalle Valo <kvalo@kernel.org>
Link: https://lore.kernel.org/r/20220818073352.3156288-1-zheyuma97@gmail.com