tidy up chromeos_setup.sh

- remove unused alex
- streamline Link's config
- remove misleading Daisy config:
  1) armv7=1 does nothing.  We meant to type arm_version=7 here.
  2) arm_neon=1 does nothing unless arm_version == 7.
  3) arm_thumb=0 is the default when arm_version <= 7.
  4) skia_arch_width=32 is the default when skia_arch_type=arm.

I'd just fix this to make Daisy arm_version=7 and arm_neon=1 (and
arm_thumb=1, which I'm going to separately make the default for
arm_version=7), but there are known color-order bugs with our
NEON procs that would make Daisy start pushing bad images to
Gold.  Going to take baby steps here...

BUG=skia:1843

Review URL: https://codereview.chromium.org/1051253002

platform_tools/chromeos/bin/chromeos_setup.sh

@@ -1,4 +1,10 @@
 # Set up the environment to build Skia for ChromeOS.
+###############################################################################
+# Copyright 2015 Google Inc.
+#
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+###############################################################################
 
 function exportVar {
   NAME=$1
@@ -23,16 +29,13 @@ setup_device() {
   DEFINES="OS=linux host_os=linux skia_os=chromeos skia_gpu=0"
 
   case $TARGET_DEVICE in
-    x86-alex)
-        DEFINES="${DEFINES} skia_arch_type=x86 skia_arch_width=32"
-        GENERIC_BOARD_TYPE="x86-generic"
-        ;;
     link)
-        DEFINES="${DEFINES} skia_arch_type=x86 skia_arch_width=64"
+        DEFINES="${DEFINES} skia_arch_type=x86_64"
         GENERIC_BOARD_TYPE="amd64-generic"
         ;;
     daisy)
-        DEFINES="${DEFINES} skia_arch_type=arm arm_neon=1 armv7=1 arm_thumb=0 skia_arch_width=32"
+        # TODO(mtklein): make this arm_version=7 and arm_neon=1
+        DEFINES="${DEFINES} skia_arch_type=arm"
         # TODO(borenet): We have to define skia_warnings_as_errors=0 for the arm
         # build, which throws lots of "mangling of va_list has changed" warnings.
         DEFINES="${DEFINES} skia_warnings_as_errors=0"