staging: rtl8712: remove _malloc()

This patch removes all usage of _malloc() and the function itself. Most
uses are straightforward replacements by kmalloc(..., GFP_ATOMIC),
because this was the definition of _malloc(). In a few places it
was possible to use kzalloc() or memdup_user.

A further improvement would be to replace GFP_ATOMIC with GFP_KERNEL
where possible.

Verified by compilation only.

Initial replacement done by running a Coccinelle script along the lines
of:

@@
type T;
expression E;
identifier V;
@@
- V = (T) _malloc(E);
+ V = kmalloc(E, GFP_ATOMIC);

@@
expression E, E1;
@@
- E1 = _malloc(E);
+ E1 = kmalloc(E, GFP_ATOMIC);

Signed-off-by: Vitaly Osipov <vitaly.osipov@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>