staging: rtl8188eu: clean up the useless code

The two bool variables singletone and carrier_sup are always false
and the following if statement can't be true, these code are useless,
so remove them.

Reported-by: Tosk Robot <tencent_os_robot@tencent.com>
Signed-off-by: Kaixu Xia <kaixuxia@tencent.com>
Link: https://lore.kernel.org/r/1605442400-16108-1-git-send-email-kaixuxia@tencent.com


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>