staging: rtl8723bs: remove semaphore remnants

Nothing uses the semaphores any more in this driver, so remove
all references to that type.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Reviewed-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>