usb: iowarrior: replace kmalloc with kmalloc_array

A common flaw in the kernel is integer overflow during memory allocation
size calculations. In an effort to reduce the frequency of these bugs,
kmalloc_array was implemented, which allocates memory for an array,
while at the same time detects integer overflow.

This patch replaces cases of:

	kmalloc(a * b, gfp)

with:
	kmalloc_array(a, b, gfp)

Reviewed-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>