[BNX2]: Fix bug in bnx2_nvram_write().

The bug was a bogus pointer being passed to kfree().  The pointer was
incremented in the write loop and then passed to kfree().

The fix is to use align_buf to save the original address.

Signed-off-by: Michael Chan <mchan@broadcom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>