The last argument in the PSCHED_TDIFF_SAFE is no longer used;
only usage eliminated by previous patch. It gets rid of a bad macro
usage.

Also, can use the standard min_t macro which also eliminates the
macro problem of double evaluation of bound.
Signed-off-by: Stephen Hemminger <shemminger@osdl.org>
Signed-off-by: David S. Miller <davem@redhat.com>