[IRDA]: Do not do pointless kmalloc return value cast in KingSun driver

kmalloc() returns a void pointer, so there is no need to cast it in
 drivers/net/irda/kingsun-sir.c::kingsun_probe().

Signed-off-by: Jesper Juhl <jesper.juhl@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>