intel/fs: Teach instruction scheduler about GRF bank conflict cycles.

This should allow the post-RA scheduler to do a slightly better job at
hiding latency in presence of instructions incurring bank conflicts.
The main purpuse of this patch is not to improve performance though,
but to get conflict cycles to show up in shader-db statistics in order
to make sure that regressions in the bank conflict mitigation pass
don't go unnoticed.

Acked-by: Matt Turner <mattst88@gmail.com>

src/intel/compiler/brw_fs.h

@@ -146,6 +146,7 @@ public:
    bool opt_drop_redundant_mov_to_flags();
    bool opt_register_renaming();
    bool opt_bank_conflicts();
+   unsigned bank_conflict_cycles(const fs_inst *inst) const;
    bool register_coalesce();
    bool compute_to_mrf();
    bool eliminate_find_live_channel();