fm10k: correctly pack TLV structures and explain reasoning

The TLV format for little endian structures is actually 4 byte aligned
copy. To this end, we need to add an additional __aligned(4) marker
along with __packed to ensure that these structures are actually 4 byte
aligned and packed correctly. Use of just __packed will not work as this
will result in 1byte alignment which is incorrect. Add a comment
explaining the reasoning behind why these structures need the special
treatment.

Signed-off-by: Jacob Keller <jacob.e.keller@intel.com>
Tested-by: Krishneil Singh <Krishneil.k.singh@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>