i40e: remove unnecessary __packed

'struct i40e_dma_mem' defined with 'packed' directive causing kernel
unaligned errors on sparc.

e.g.
i40e: Intel(R) Ethernet Connection XL710 Network Driver - version
1.6.16-k
i40e: Copyright (c) 2013 - 2014 Intel Corporation.
Kernel unaligned access at TPC[44894c] dma_4v_alloc_coherent+0x1ac/0x300
Kernel unaligned access at TPC[44894c] dma_4v_alloc_coherent+0x1ac/0x300
Kernel unaligned access at TPC[44894c] dma_4v_alloc_coherent+0x1ac/0x300
Kernel unaligned access at TPC[44894c] dma_4v_alloc_coherent+0x1ac/0x300
Kernel unaligned access at TPC[44894c] dma_4v_alloc_coherent+0x1ac/0x300
i40e 0000:03:00.0: fw 5.1.40981 api 1.5 nvm 5.04 0x80002548 0.0.0

This can be fixed with get_unaligned/put_unaligned(). However no
reference in driver shows that 'struct i40e_dma_mem' directly shoved
into NIC hardware. But instead fields of the struct are being read and
used for hardware. Therefore, __packed is unnecessary for 'struct
i40e_dma_mem'.

In addition, although 'struct i40e_virt_mem' doesn't cause any
unaligned access, keeping it packed is unnecessary as well because
of aforementioned reason.

This change make 'struct i40e_dma_mem' and 'struct i40e_virt_mem'
unpacked.

Signed-off-by: Tushar Dave <tushar.n.dave@oracle.com>
Tested-by: Andrew Bowers <andrewx.bowers@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>