Move modem_set_carrier to crosh from crosh-workarounds

BUG=chromium-os:13312
TEST=installed, and ran modem_set_carrier from crosh. Verified help output looks right.

Review URL: http://codereview.chromium.org/6708067

Change-Id: I5077b658c72eea30afa9c7c2ef3aca3f09679280
(cherry picked from commit 5935579ff945752851fc9e859b7569097b5efa17)

Review URL: http://codereview.chromium.org/6722005
diff --git a/crosh-workarounds b/crosh-workarounds
index 8e574b4..449f858 100755
--- a/crosh-workarounds
+++ b/crosh-workarounds
@@ -3,7 +3,7 @@
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
-# Crosh commands to create and install USB stick with preferred build.
+# Extra crosh commands
 
 if [ "$(basename $0)" = "crosh-workarounds" ]; then
   exec "$(dirname $0)/crosh" --workarounds
@@ -54,16 +54,6 @@
   fi
 }
 
-if [ -x /usr/bin/modem_set_carrier ]; then
-HELP="$HELP"'
- modem_set_carrier carrier-name
-  Configures the modem for the specified carrier.
-'
-cmd_modem_set_carrier() {
-  /usr/bin/modem_set_carrier "$@"
-}
-fi
-
 HELP="$HELP"'
  cryptohome [--status]
   Get human-readable status information from cryptohomed