net: cisco: enic: Replace GFP_ATOMIC with GFP_KERNEL

vnic_dev_register(), vnic_rq_alloc_bufs() and vnic_wq_alloc_bufs()
are never called in atomic context.
They call kzalloc() with GFP_ATOMIC, which is not necessary.
GFP_ATOMIC can be replaced with GFP_KERNEL.

This is found by a static analysis tool named DCNS written by myself.

Signed-off-by: Jia-Ju Bai <baijiaju1990@gmail.com>
Acked-by: Govindarajulu Varadarajan <gvaradar@cisco.com>
Signed-off-by: David S. Miller <davem@davemloft.net>