When entering recovery mode, no need to plug out/in USB if dev switch is ON.

According to our spec, the recovery screen is not shown when dev switch is ON.
This change also has several minor fixes:
 - Matching crossystem mainfw_type value based on requested dev_mode or not.
 - Checking mainfw_type "not (normal or developer)" instead of "recovery" to
   prevent unnecessary warning messages.
 - Directly run "chromeos-install" command to reduce unnecessary reboot.

BUG=chromium-os:19710
TEST=run_remote_tests.sh --remote=$REMOTE_IP -a "xml_config=$OVERLAY_XML \
          servo_vid=0x18d1 servo_pid=0x5001" RecoveryButton/control.dev
     run_remote_tests.sh --remote=$REMOTE_IP -a "xml_config=$OVERLAY_XML \
          servo_vid=0x18d1 servo_pid=0x5001" UserRequestRecovery/control.dev
     run_remote_tests.sh --remote=$REMOTE_IP -a "xml_config=$OVERLAY_XML \
          servo_vid=0x18d1 servo_pid=0x5001" CorruptBothFwSigAB/control.dev
     run_remote_tests.sh --remote=$REMOTE_IP -a "xml_config=$OVERLAY_XML \
          servo_vid=0x18d1 servo_pid=0x5001" CorruptBothFwBodyAB/control.dev
     run_remote_tests.sh --remote=$REMOTE_IP -a "xml_config=$OVERLAY_XML \
          servo_vid=0x18d1 servo_pid=0x5001" CorruptBothKernelAB/control.dev

Change-Id: Ibe2e267d39084fcd26e4f79dadccb82634d92a78
Reviewed-on: https://gerrit.chromium.org/gerrit/13221
Commit-Ready: Tom Wai-Hong Tam <waihong@chromium.org>
Reviewed-by: Tom Wai-Hong Tam <waihong@chromium.org>
Tested-by: Tom Wai-Hong Tam <waihong@chromium.org>
5 files changed