net: qualcomm: rmnet: Fix incorrect allocation flag in receive path

The incoming skb needs to be reallocated in case the headroom
is not sufficient to adjust the ethernet header. This allocation
needs to be atomic otherwise it results in this splat

 [<600601bb>] ___might_sleep+0x185/0x1a3
 [<603f6314>] ? _raw_spin_unlock_irqrestore+0x0/0x27
 [<60069bb0>] ? __wake_up_common_lock+0x95/0xd1
 [<600602b0>] __might_sleep+0xd7/0xe2
 [<60065598>] ? enqueue_task_fair+0x112/0x209
 [<600eea13>] __kmalloc_track_caller+0x5d/0x124
 [<600ee9b6>] ? __kmalloc_track_caller+0x0/0x124
 [<602696d5>] __kmalloc_reserve.isra.34+0x30/0x7e
 [<603f629b>] ? _raw_spin_lock_irqsave+0x0/0x3d
 [<6026b744>] pskb_expand_head+0xbf/0x310
 [<6025ca6a>] rmnet_rx_handler+0x7e/0x16b
 [<6025c9ec>] ? rmnet_rx_handler+0x0/0x16b
 [<6027ad0c>] __netif_receive_skb_core+0x301/0x96f
 [<60033c17>] ? set_signals+0x0/0x40
 [<6027bbcb>] __netif_receive_skb+0x24/0x8e

Fixes: 74692caf ("net: qualcomm: rmnet: Process packets over ethernet")
Signed-off-by: Sean Tranchetti <stranche@codeaurora.org>
Signed-off-by: Subash Abhinov Kasiviswanathan <subashab@codeaurora.org>
Signed-off-by: David S. Miller <davem@davemloft.net>