net/ncsi: Ensure 32-bit boundary for data cksum

The NCSI spec indicates that if the data does not end on a 32 bit
boundary, one to three padding bytes equal to 0x00 shall be present to
align the checksum field to a 32-bit boundary.

Signed-off-by: Terry S. Duncan <terry.s.duncan@linux.intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>