Remove casting the values returned by memory allocation function.

Coccinelle emits WARNING: casting value returned by memory allocation
function to struct pointer is useless.

This issue was detected by using the Coccinelle.
Signed-off-by: Aishwarya Ramakrishnan <aishwaryarj100@gmail.com>
Acked-by: Michal Kalderon <michal.kalderon@marvell.com>
Signed-off-by: David S. Miller <davem@davemloft.net>