intel/compiler: Update block IPs once in register_coalesce

Performance improvement in
dEQP-VK.ssbo.phys.layout.random.16bit.scalar.13 for n=30:

release build (w/Fedora build flags): -0.82% ± 0.23%
Meson -Dbuildtype=debugoptimized:     -0.74% ± 0.27%

The difference in the debugoptimized build is the calls to
inst_is_in_block(block, this) still exist on each call to remove().

v2: Only update each block's IP data once instead of once per block.
Suggested by Emma.

Reviewed-by: Emma Anholt <emma@anholt.net>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/11632>

src/intel/compiler/brw_fs_register_coalesce.cpp

@@ -330,10 +330,12 @@ fs_visitor::register_coalesce()
    if (progress) {
       foreach_block_and_inst_safe (block, backend_instruction, inst, cfg) {
          if (inst->opcode == BRW_OPCODE_NOP) {
-            inst->remove(block);
+            inst->remove(block, true);
          }
       }
 
+      cfg->adjust_block_ips();
+
       invalidate_analysis(DEPENDENCY_INSTRUCTIONS);
    }