m7-common: dim the default backlight configuration

The default backlight configuration is very bright. Let's turn it down a
notch. This is of course still configurable by the end user so this
shouldn't ruffle too many feathers.

For those who stumble across this commit and are curious how to convert
the percentages in the brightness dialog to the values in this xml file,
this should be easy to interpret in your favorite programming language:

testedPercVals = 0.01*{8, 10, 14, 20, 26, 30, 36, 48, 64, 100};
range = 255;
minLev = 10; <-- defined in this xml file
Round[testedPercVals*(range - minLev) + minLev]
  (result) --> {30, 34, 44, 59, 74, 84, 98, 128, 167, 255}

Here's the new brightness curve: http://imgur.com/O6Tt7zs
(you can pull up the old config on your own device for comparison)

Change-Id: I0601686df4d40fc55094f33e5e2001f9aeecc73b
m7-common: remove unused AudioBTID files

These seem to only be used by msm8660/msm7x30 in audio-caf.

Change-Id: Ia5b0aa76febe7ce491d63ad7a590d90665385bad
m7-common: fix breakfast sync error if no vendor

Let breakfast retrieve repositories without error if vendor is not yet
populated (which for most users it should not be, as the extract scripts
have not yet been run).

Change-Id: I34650c8c41b9bb6ff501d60fd9ec91b546297d8f