be2net: Fix to prevent Tx stall on SH-R when packet size < 32

Tx on SH-R can lockup if the packet size is less than 32 bytes.
Pad such packets to a safer 36-byte size.
Patch uses the Lancer-R workaround - which checks for packet <= 32-bytes

Signed-off-by: Ajit Khaparde <ajit.khaparde@emulex.com>
Signed-off-by: David S. Miller <davem@davemloft.net>