staging: rtl8723bs: os_dep: ioctl_linux: make use of kzalloc

This patch is a cleanup which replaces rtw_malloc(wep_total_len) with
kzalloc() and removes the memset().

The rtw_malloc() does GFP_ATOMIC allocations when in_atomic() is true.
But as the comments for in_atomic() describe, the in_atomic() check
should not be used in driver code.  The in_atomic() check is not
accurate when preempt is disabled.

In this code we are not in IRQ context and we are not holding any
spin_locks so GFP_KERNEL is safe.

Signed-off-by: Hariprasad Kelam <hariprasad.kelam@gmail.com>
----
changes in v2: Replace rtw_zmalloc with kzalloc
changes in v3: Add proper changelog
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>