vxlan: vnifilter: Use GFP_KERNEL instead of GFP_ATOMIC

vxlan: vnifilter: Use GFP_KERNEL instead of GFP_ATOMIC

The function is not called from an atomic context so use GFP_KERNEL
instead of GFP_ATOMIC. The allocation of the per-CPU stats is already
performed with GFP_KERNEL.

Tested using test_vxlan_vnifiltering.sh with CONFIG_DEBUG_ATOMIC_SLEEP.

Signed-off-by: Ido Schimmel <idosch@nvidia.com>
Reviewed-by: Simon Horman <horms@kernel.org>
Reviewed-by: Kalesh AP <kalesh-anakkur.purayil@broadcom.com>
Reviewed-by: Nikolay Aleksandrov <razor@blackwall.org>
Link: https://lore.kernel.org/r/20230821141923.1889776-1-idosch@nvidia.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>