Proper fix for issue 20051601 - arm actually means thumb2.

Change-Id: I38e81868cbebdccec6ecbba40494612f7c1d8092
diff --git a/compiler/elf_writer_quick.cc b/compiler/elf_writer_quick.cc
index 3ce19ab..24cb364 100644
--- a/compiler/elf_writer_quick.cc
+++ b/compiler/elf_writer_quick.cc
@@ -490,14 +490,11 @@
     int code_factor_bits_ = 0;
     int isa = -1;
     switch (oat_writer->GetOatHeader().GetInstructionSet()) {
+      case kArm:  // arm actually means thumb2.
       case kThumb2:
         code_factor_bits_ = 1;  // 16-bit instuctions
         isa = 1;  // DW_ISA_ARM_thumb.
         break;
-      case kArm:
-        code_factor_bits_ = 1;  // 16-bit instructions
-        isa = 2;  // DW_ISA_ARM_arm.
-        break;
       case kArm64:
       case kMips:
       case kMips64: