wifi: avoid kernel-infoleak from struct iw_point

In the Linux kernel, the following vulnerability has been resolved:

wifi: avoid kernel-infoleak from struct iw_point

struct iw_point has a 32bit hole on 64bit arches.

struct iw_point { void __user *pointer; /* Pointer to the data (in user space) */ __u16 length; /* number of fields or size in bytes */ __u16 flags; /* Optional params */ };

Make sure to zero the structure to avoid disclosing 32bits of kernel data to user space.