aco: don't consider a phi trivial if same's register doesn't match the def

For example:
 s2: %688:s[32-33] = p_linear_phi %3:s[10-11], %688:s[32-33]
would have been considered trivial.

This might happen due to parallelcopies when assigning phi registers.

Signed-off-by: Rhys Perry <pendingchaos02@gmail.com>
Reviewed-by: Daniel Schürmann <daniel@schuermann.dev>
Fixes: 69b6069dd2 ("aco: refactor try_remove_trivial_phi() in RA")
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/8645>

src/amd/compiler/aco_register_allocation.cpp

@@ -1778,7 +1778,7 @@ void try_remove_trivial_phi(ra_ctx& ctx, Temp temp)
          assert(t == same || op.physReg() == def.physReg());
          continue;
       }
-      if (same != Temp())
+      if (same != Temp() || op.physReg() != def.physReg())
          return;
 
       same = t;