Remove non-existent ARM insn kThumb2SubsRRI12.

For kOpSub/kOpAdd, prefer modified immediate encodings
because they set flags.

Change-Id: I41dcd2d43ba1e62120c99eaf9106edc61c41e157
diff --git a/compiler/dex/quick/arm/call_arm.cc b/compiler/dex/quick/arm/call_arm.cc
index b36dde9..9f75422 100644
--- a/compiler/dex/quick/arm/call_arm.cc
+++ b/compiler/dex/quick/arm/call_arm.cc
@@ -85,7 +85,8 @@
   LIR* switch_branch = NewLIR1(kThumb2AddPCR, r_disp);
   tab_rec->anchor = switch_branch;
   // Needs to use setflags encoding here
-  NewLIR3(kThumb2SubsRRI12, r_idx, r_idx, 1);
+  OpRegRegImm(kOpSub, r_idx, r_idx, 1);  // For value == 1, this should set flags.
+  DCHECK(last_lir_insn_->u.m.def_mask & ENCODE_CCODE);
   OpCondBranch(kCondNe, target);
 }