Switch helpers tc_core_{time2ktime,ktime2time} from long to unsigned as well.

Switch helpers tc_core_{time2ktime,ktime2time} from long to unsigned as well.

Follow up patch to "Fix overflow in time2tick / tick2time." which switches
the remaining two helper functions from long to unsigned as well.
These functions are only used in "tc/q_hfsc.c" where both the passed argument
and the place the return value is stored are unsigned/u32 variables, so this
change should be safe to make but hasn't been tested as extensively as the
time2tick patch.

Signed-off-by: Andreas Henriksson <andreas@fatal.se>
Signed-off-by: Stephen Hemminger <shemminger@linux-foundation.org>