i40evf: don't use atomic allocation

These allocations don't need to be at atomic level. GFP_KERNEL is fine
and they'll reduce stress on the allocator when the system is starved
for memory.

Change-ID: I3561d0399a681de0ad25291b6c848b224c1fde12
Signed-off-by: Mitch Williams <mitch.a.williams@intel.com>
Tested-by: Andrew Bowers <andrewx.bowers@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>