Disable screen blanking and powersave on VT2 for factory

Disable screen blanking and powersave on VT2 for factory

For non-factory systems with VT2 functionality this does NOT change
the blanking or powersave despite believing it would.

For factory, it does correctly disable powersave and blanking.

See tracker for more details

Related CLS:
http://codereview.chromium.org/6838023/
http://codereview.chromium.org/6857005/

BUG=chrome-os-partner:2950
TEST=manual,
1. create factory image place on USB stick
2. boot to 'dev' screen hit ctrl-U
3. run factory flow ( wouldn't complete on my system )
4. switch to VT2 and make sure screen stays on >10min
5. switch to VT1 (factory test) make sure still operational
6. switch to VT2, and sudo stop factory
7. make sure VT2 screen stays on >10min

Change-Id: I822291e4b70111e920cf2c24802996789b6f87a5

Committed: http://chrome-svn/viewvc/chromeos?view=rev&revision=d822d40

[Hung-Te, 2011-04-16 01:31:11]

LGTM

[jrbarnette, 2011-04-16 01:54:09]

Small nits, then LGTM:
Could you add a 1-line comment to explain what the magic control
sequences do?

Also, you're saying this is factory specific?  Is that because of some
kernel configuration option, or is it subtler than that?  A 1-line
comment explaining that would help, too.

[Hung-Te, 2011-04-16 02:00:59]

This is for disabling screen blanking/powersave for anyone using VT2, especially
useful for factory images (maybe also for recovery images). However, it's not
working properly in normal images now.