Fix idiv latencies for znver3

Fix idiv latencies for znver3

update costs of integer divides to match actual latencies (the scheduler model
already does the right thing).  It is essentially no-op, since we end up
expanding idiv for all sensible constants, so this only may end up disabling
vectorization in some cases, but I did not find any such examples.  However in
general it is better ot have actual latencies than random numbers.

gcc/ChangeLog:

2021-03-18  Jan Hubicka  <hubicka@ucw.cz>

	* config/i386/x86-tune-costs.h (struct processor_costs): Fix costs of
	integer divides1.