net: nixge: Use GFP_KERNEL instead of GFP_ATOMIC when possible

NIXGE_MAX_JUMBO_FRAME_SIZE is over 9000 bytes and RX_BD_NUM 128.

So this loop allocates more than 1 Mo of memory.

Previous memory allocations in this function already use GFP_KERNEL, so
use __netdev_alloc_skb_ip_align() and an explicit GFP_KERNEL instead of a
implicit GFP_ATOMIC.

This gives more opportunities of successful allocation.

Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Link: https://lore.kernel.org/r/28d2c8e05951ad02a57eb48333672947c8bb4f81.1645043881.git.christophe.jaillet@wanadoo.fr
Signed-off-by: Jakub Kicinski <kuba@kernel.org>