staging: r8118eu: remove useless parts of judgements from os_dep/ioctl_linux.

Remove the check of the pointer 'pregpriv' that is impossible to be
NULL. There is no need to check if pregpriv is NULL.

Reported-by: Zeal Robot <zealci@zte.com.cn>
Signed-off-by: xu xin <xu.xin16@zte.com.cn>
Thanks-to: Pavel Skripkin <paskripkin@gmail.com>
Link: https://lore.kernel.org/r/20210830012811.3384-1-xu.xin16@zte.com.cn


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