kbuild test robot reported a build failure on s390.
While at it, also fix missing conversion in the tilera driver.

Fixes: 9b36627a ("net: remove dev->trans_start")
Reported-by: Nkbuild test robot <fengguang.wu@intel.com>
Signed-off-by: NFlorian Westphal <fw@strlen.de>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>