isl_scheduler.c: update_schedule: drop support for transformed coefficients
Before the previous commit, the Pluto-like ILP problem would use
transformed schedule coefficients, while the Feautrier LP problem
would use the original schedule coefficients. The extraction in
update_schedule therefore had to support both cases.
Now that the Pluto-like ILP problem also uses the original
schedule coefficients, update_schedule no longer needs to support
transformed schedule coefficients.
Signed-off-by: Sven Verdoolaege <sven.verdoolaege@gmail.com>