net: hso: Use GFP_KERNEL instead of GFP_ATOMIC when possible

hso_create_device() is only called from function that already use
GFP_KERNEL. And all the callers are called from the probe function.

So there is no need here to explicitly require a GFP_ATOMIC when
allocating memory.

Use GFP_KERNEL instead.

Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Signed-off-by: David S. Miller <davem@davemloft.net>